Antibodies to Plasminogen Activator Inhibitor-1 (PAI-1) and Uses Thereof

ABSTRACT

The invention provides antibodies that specifically bind to Plasminogen Activator inhibitor type-1 (PAI-1). The invention also provides pharmaceutical compositions, as well as nucleic acids encoding anti-PAI-1 antibodies, recombinant expression vectors and host cells for making such antibodies, or fragments thereof. Methods of using antibodies to modulate PAT-1 activity or detect PAI-1, either in vitro or in vivo, are also provided. The disclosure further provides methods of making antibodies that specifically bind to PAT-1 in the active conformational state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/865,451, filed Aug. 13, 2013, and European Patent Application No.14305757.8, filed May 22, 2014, which are incorporated herein byreference in their entireties.

BACKGROUND

Plasminogen Activator Inhibitor type-1 (PAI-1) is the main inhibitor oftissue-type plasminogen activator (tPA) and urokinase-type plasminogenactivator (uPA), the key serine proteases responsible for plasmingeneration. PAI-1 regulates fibrinolysis by inhibiting plasminogenactivation in the vascular compartment. Fibrinolysis is a tightlycoordinated process for degrading fibrin clots formed by activation ofthe coagulation cascade. Dysregulation of the coagulation/fibrinolysisbalance leads to abnormal haemostasis events like bleeding or thromboticdiseases. PAI-1 is also a key regulator of plasminogen activation in thepericellular compartment (intravascular and tissular) where receptorbound plasminogen is activated mainly by urokinase bound to theurokinase receptor (uPAR). By inhibiting pericellular proteolysis, PAI-1regulates numerous cellular functions like extracellular matrix (ECM)degradation, growth factors activation and release from ECM, matrixmetalloproteinases (MMP) activation and cellular apoptosis. Recently,protease-independent effects of PAI-1 have been identified through itsinteraction with cofactors (like vitronectin, heparin,glycosaminoglycan), uPAR-urokinase complexes or cellular receptors (LRP:low-density Lipoprotein Receptor-related Protein) or integrins affectingcell functions like adhesion/de-adhesion, migration, proliferation andintracellular bioactivity. By these cellular mechanisms andanti-fibrinolytic effects, a pathogenic role of PAI-1 has beenestablished in tumor growth and metastasis, fibrosis, acute myocardialinfarction and metabolic disorders like atherosclerosis, obesity anddiabetes.

The Human SERPINE1 (PAI-1) gene is localized to chromosome 7, consistsof eight introns and nine exons, and has a size of 12.169 b (Klinger. K.W. et al. Proc. Natl. Acad. Sci. USA 84:8548, 1987). PAI-1 is a singlechain glycoprotein of approximately 50 kDa (379 amino acids) from theSERPIN (serine protease inhibitor) superfamily that is synthesized inthe active conformation but spontaneously becomes latent in the absenceof vitronectin (Vn). Vitronectin, the main cofactor of PAI-1, stabilizesthe active conformation with the Reactive Center Loop (RCL) which isapproximately 20 amino acids that are exposed on the surface. Themechanism of inhibition of PAI-1's two main targets (tPA and uPA) is asuicide inhibition. The RCL region of PAI-1 bears the bait peptide bond(R346-M347, also called P1-P′1), which bears the cleavage site for thisserine protease. A Michaelis complex with tPA or uPA forms first, thenthe catalytic triad reacts with the bait peptide bond to form anacyl-enzyme complex that, after cleavage of the P1-P′1 peptide bond,induces strong conformation changes. The conformational changes causeinsertion of the cleaved RCL into a β-strand with the protease stayingcovalently bound as an acyl enzyme with PAI-1. Under non-physiologicalcircumstances, hydrolysis of this acyl-enzyme complex may induce releaseof the cleaved PAI-1 and free active protease (Blouse et al.,Biochemistry, 48:1723, 2009).

PAI-1 circulates in blood at highly variable levels (nM range) and inexcess over t-PA or uPA concentrations. PAI-1 exhibits structuralflexibility and can be found in one of three conformations: (1) a latentconformation, (2) an active conformation, or (3) a substrateconformation (see FIG. 1). PAI-1 is mainly found as a noncovalentcomplex with vitronectin (Kd˜1 nM) that decreases latency transition by1.5 to 3 fold. Latent, cleaved or complexed PAI-1 affinity forvitronectin is significantly reduced. Matrix bound vitronectin alsolocalizes with PAI-1 in the pericellular space. Endothelial cells,monocytes, macrophages and vascular smooth muscle cells synthesize thisPAI-1 which then can be stored in large amounts under latent form byplatelets (in the α granule). PAI-1 is a fast and specific inhibitor(with the second order rate constant of 10⁶ to 10⁷ M⁻¹s⁻¹ of tPA and uPAin solution, but inactive against protease bound either to fibrin ortheir cellular receptors. Other proteases like thrombin, plasmin,activated Protein C can be also inhibited by PAI-1 but less efficiently.

Several 3D structures of human PAI-1 have been solved since the firstone described in 1992 (Mottonen et al., Nature 355:270, 1992) in thelatent conformation. These 3D structures include mutant forms of PAI-1in the substrate (Aertgecrts et al., Proteins 23:118, 1995), stabilizedactive conformation (Sharp et al., Structure 7:111, 1999), PAI complexedto Vitronectin-somatomedin B domain (Zhou et al., Nat. Struct. Biol.10:541, 2003) or with inhibiting pentapeptide from the RCL loop (Xue etal., Structure 6:627, 1998). More recently, mouse PAI-1 structure inlatent conformation was elucidated by Dewilde et al. (J Struct. Biol.171:95, 2010) and revealed differences with human PAI-1 in the RCLposition, gate region and position of α-helix A. Structure/functionrelationships in PAI-1 have been studied by using more than 600 mutantproteins (reviewed by De Taeye et al., Thromb. Haemost. 92:898, 2004) tolocalize domains involved in the various activities of thismultifunctional serpin.

Since PAI-1 can be synthesized by almost every cell type includinghepatocyte, adipocyte, mesangial cell, fibroblast, myofibroblast, andepithelial cell, its expression greatly varies under physiological(e.g., circadian variation of plasma PAI-1 level) and pathologicalconditions (e.g., obesity, metabolic syndrome, insulin resistance,infection, inflammatory diseases, cancer). PA-1 is considered to be anacute phase protein. Transcriptional regulation of PAI-1 mRNA expressionis induced by several cytokines and growth factors (e.g., TGFβ, TNFα,EGF, FGF, Insulin, angiotensin II & IV), hormones (e.g., aldosterone,glucocorticoids, PMA, high glucose) and stress factors (e.g., hypoxia,reactive oxygen species, lipopolysaccharides).

Moreover, a polymorphism in the promoter (position-675) of the PAI-1gene affects expression level. The 4G allele increases PAI-1 level andthe 4G/4G variant (occurring in around 25% of the population) induces anincrease of approximately 25% of plasma PAI-1 level in comparison to5G/5G (25% occurrence and 4G/5G 50% occurrence). The 4G/4G polymorphismhas been linked to myocardial infarction (Dawson et al, ArteriosclerThromb. 11:183, 1991), a specific type of pulmonary fibrosis (idiopathicinterstitial pneumonia) (Kin et al., Mol Med. 9:52, 2003) and the 4G/4Ggenotype donor group is an independent risk factor for kidney graft lossdue to Interstitial Fibrosis &Tubular Atrophy (Rerolle et al., Nephrol.Dial. Transplant 23:3325, 2008).

Several pathogenic roles have been attributed to PAI-1 in thromboticdiseases such as arterial and venous thrombosis, acute myocardialinfarction, and atherosclerosis. Its involvement in metabolic disorderslike insulin resistance syndrome and obesity is well recognized. PAI-1is also known as a profibrotic factor for several organs and has beenshown to be over-expressed in fibrotic tissues (i.e., liver, lung,kidney, heart, abdominal adhesions, skin: scar or scleroderma) (reviewedby Ghosh and Vaughan, J. Cell Physiol. 227:493, 2012). PAI-1 knock-out(KO) mice are protected from fibrosis in different models, such as liver(bile duct ligation or xenobiotic), kidney (unilateral ureteralobstruction model (UUO)), lung (bleomycin inhalation) (Bauman et al., J.Clin. Invest. 120:1950, 2010; Hattori et al., Am. J. Pathol. 164:1091,2004; Chuang-Tsai et al., Am. J. Pathol. 163:445, 2003) whereas in heartthis deletion is protected from induced fibrosis (Takeshita et al., AM.J. Pathol. 164:449, 2004) but prone to age-dependent cardiac selectivefibrosis (Moriwaki et al., Cric. Res. 95:637, 2004). Down-regulation ofPAI-1 expression by siRNA (Senoo et al., Thorax 65:334, 2010) orinhibition by chemical compounds (Izuhara et al., Arterioscler: Thromb.Vasc. Biol. 28:672, 2008; Huang et al., Am. J. Respir. Cell Mol. Biol.46:87, 2012) have been reported to decrease lung fibrosis whereas PAT-1overexpression of wild type (Eitzman et al., J. Clin. Invest. 97:232,1996) or a PAI-1 mutant retaining only vitronectin binding but not tPAinhibitor function exacerbates lung fibrosis (Courey et al., Blood118:2313, 2011).

Bile duct ligation (BDL) liver fibrosis is attenuated by antibodyneutralizing PAI-1 (U.S. Pat. No. 7,771,720) whereas down-regulation bysiRNA attenuates BDL and xenobiotic induced liver fibrosis (Hu et al.,J. Hepatol. 51:102, 2009). PAI-1 KO mice were protected fromcholestatic-induced liver damage and fibrosis in BDL (Bergheim et al.,J. Pharmacol. Exp. Ther. 316:592, 2006; Wang et al., FEBS Lett.581:3098, 2007; Wang et al., Hepatology 42:1099, 2005) and fromangiotensin II induced liver fibrosis (Beier et al., Arch. Bioch.Biophys. 510:19, 2011).

PAI-1 KO mice are protected from renal fibrosis in the UUO model (Oda etal., Kidney Int. 60, 587, 2001), in diabetic nephropathy (Nicholas etal., Kidney Int. 67:1297, 2005) and in angiotensin II inducednephropathy (Knier et al., J. Hypertens. 29:1602, 2011; for reviews seeMa et al. Frontiers Biosci. 14:2028, 2009 and Eddy A. A. Thromb.Haemost. 101:656, 2009). In contrast. PAI-1 over expressing mice displaymore severe fibrosis and increased macrophage recruitment following UUO(Matsuo et al., Kidney Int. 67: 2221, 2005; Bergheim et al., J.Pharmacol. Exp. Ther. 316:592, 2006). Non-inhibitory PAI-1 mutant (PAI-1R) has been shown to protect mice from the development of fibrosis inexperimental glomerulonephritis (thy 1) in rat by decreasing urinaryprotein expression and glomerular matrix accumulation (Huang et al.,Kidney Int. 70:515, 2006). Peptides blocking PAI-1 inhibit collagen 3, 4and fibronectin accumulation in UUO mice (Gonzalez et al., Exp. Biol.Med. 234:1511, 2009).

PAI-1, as a target for numerous pathologies, has been the focus ofintensive research to inhibit its activity or to regulate its expressionfor the last 20 years. Chemical compounds (Suzuki et al., Expert Opin.Investig. Drugs 20:255, 2011), monoclonal antibodies (Gils and Declerk,Thromb Haemost; 91:425, 2004), peptides, mutants (Cale and Lawrence.Curr. Drug Targets 8:971, 2007), siRNA or anti-sense RNA have beendesigned to inhibit its various function or to regulate its expression.However, despite the intensive research, the problem of developing atherapeutically effective modulator of PAI-1 still remains to be solved.Accordingly, there is a need in the art for novel agents that inhibitthe PAI-1 activity for use in the treatment of PAI-1-mediated humanpathologies.

SUMMARY OF THE DISCLOSURE

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 34), CDR2(SEQ TD NO: 33), and CDR3 (SEQ ID NO: 32) of SEQ ID NO: 6, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 37), CDR2 (SEQ ID NO: 36), and CDR3 (SEQ ID NO: 35) of SEQID NO: 7. In an additional aspect the heavy chain comprises a heavychain variable region comprising SEQ ID NO: 6, and the light chaincomprises a light chain variable region comprising SEQ ID NO: 7. In afurther aspect, heavy chain variable region is 99%, 98%, 97%, 96%, 95%,94%, 93%, 92%, 91%, or 90% identical to SEQ ID NO: 6, and the lightchain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or90% identical to SEQ ID NO: 7. All % identity approximations indicatethe minimum % identity; higher % identity than the recited values arealso encompassed by the disclosure.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 34, a heavychain CDR2 region comprising SEQ ID NO: 33, and a heavy chain CDR3region comprising SEQ ID NO: 32; and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 37, a light chain CDR2region comprising SEQ ID NO: 36, and a light chain CDR3 regioncomprising SEQ ID NO: 35. In certain aspects, the antibody heavy chaincomprises heavy chain framework regions that are 99%, 98%, 97%, 96%,95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chain frameworkregions of SEQ ID NO: 6, and the antibody light chain comprises lightchain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the framework regions of SEQ ID NO: 7.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 22), CDR2(SEQ ID NO: 21), and CDR3 (SEQ ID NO: 20) of SEQ ID NO: 2, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 25), CDR2 (SEQ ID NO: 24), and CDR3 (SEQ ID NO: 23) of SEQID NO: 3. In an additional aspect the heavy chain comprises a heavychain variable region comprising SEQ ID NO: 2, and the light chaincomprises a light chain variable region comprising SEQ ID NO: 3. In afurther aspect, heavy chain variable region is 99%, 98%, 97%, 96%, 95%,94%, 93%, 92%, 91%, or 90% identical to SEQ ID NO: 2, and the lightchain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or90% identical to SEQ ID NO: 3.

In an additional aspect, disclosed herein is an isolated monoclonalantibody that binds specifically to PAI-1, comprising: (a) heavy chainframework regions, a heavy chain CDR1 region comprising SEQ ID NO: 22, aheavy chain CDR2 region comprising SEQ ID NO: 21, and a heavy chain CDR3region comprising SEQ ID NO: 20; and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 25, a light chain CDR2region comprising SEQ ID NO: 24, and a light chain CDR3 regioncomprising SEQ ID NO: 23. In certain aspects, the antibody heavy chaincomprises heavy chain framework regions that are 99%, 98%, 97%, 96%,95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chain frameworkregions of SEQ ID NO: 26, and the antibody light chain comprises lightchain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the framework regions of SEQ ID NO: 3.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 28), CDR2(SEQ ID NO: 27), and CDR3 (SEQ ID NO: 26) of SEQ ID NO: 4, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 31), CDR2 (SEQ ID NO: 30), and CDR3 (SEQ ID NO: 29) of SEQID NO: 5. In an additional aspect the heavy chain comprises a heavychain variable region comprising SEQ ID NO: 4, and the light chaincomprises a light chain variable region comprising SEQ ID NO: 5. In afurther aspect, heavy chain variable region is 99%, 98%, 97%, 96%, 95%,94%, 93%, 92%, 91%, or 90% identical to SEQ ID NO: 4, and the lightchain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or90% identical to SEQ ID NO: 5.

In an additional aspect, disclosed herein is an isolated monoclonalantibody that binds specifically to PAI-1, comprising: (a) heavy chainframework regions, a heavy chain CDR1 region comprising SEQ ID NO: 28, aheavy chain CDR2 region comprising SEQ ID NO: 27, and a heavy chain CDR3region comprising SEQ ID NO: 26; and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 31, a light chain CDR2region comprising SEQ ID NO: 30, and a light chain CDR3 regioncomprising SEQ ID NO: 29. In certain aspects, the antibody heavy chaincomprises heavy chain framework regions that are 99%, 98%, 97%, 96%,95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chain frameworkregions of SEQ ID NO: 4, and the antibody light chain comprises lightchain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the framework regions of SEQ ID NO: 5.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 40), CDR2(SEQ ID NO: 39), and CDR3 (SEQ ID NO: 38) of SEQ ID NO: 8, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 43), CDR2 (SEQ ID NO: 42), and CDR3 (SEQ ID NO: 41) of SEQID NO: 9. In an additional aspect the heavy chain comprises a heavychain variable region comprising SEQ ID NO: 8, and the light chaincomprises a light chain variable region comprising SEQ ID NO: 9. In afurther aspect, heavy chain variable region is 99%, 98%, 97%, 96%, 95%,94%, 93%, 92%, 91%, or 90% identical to SEQ ID NO: 8, and the lightchain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or90% identical to SEQ ID NO: 9.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 40, a heavychain CDR2 region comprising SEQ ID NO: 39, and a heavy chain CDR3region comprising SEQ ID NO: 38: and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 43, a light chain CDR2region comprising SEQ ID NO: 42, and a light chain CDR3 regioncomprising SEQ ID NO: 41. In certain aspects, the antibody heavy chaincomprises heavy chain framework regions that are 99%, 98%, 97%, 96%,95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chain frameworkregions of SEQ ID NO: 8, and the antibody light chain comprises lightchain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the framework regions of SEQ ID NO: 9.

In one aspect, disclosed herein is An isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 52), CDR2(SEQ ID NO: 51), and CDR3 (SEQ ID NO: 50) of SEQ ID NO: 10, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 55), CDR2 (SEQ ID NO: 54), and CDR3 (SEQ ID NO: 53) of SEQID NO: 11. In an additional aspect the heavy chain comprises a heavychain variable region comprising SEQ ID NO: 10, and the light chaincomprises a light chain variable region comprising SEQ ID NO: 11. In afurther aspect, heavy chain variable region is 99%, 98%, 97%, 96%, 95%,94%, 93%, 92%, 91%, or 90% identical to SEQ ID NO: 10, and the lightchain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or90% identical to SEQ ID NO: 11.

In an additional aspect, disclosed herein is an isolated monoclonalantibody that binds specifically to PAI-1, comprising: (a) heavy chainframework regions, a heavy chain CDR1 region comprising SEQ ID NO: 52, aheavy chain CDR2 region comprising SEQ ID NO: 51, and a heavy chain CDR3region comprising SEQ ID NO: 50; and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 55, a light chain CDR2region comprising SEQ ID NO: 54, and a light chain CDR3 regioncomprising SEQ ID NO: 53. In certain aspects, the antibody heavy chaincomprises heavy chain framework regions that are 99%, 98%, 97%, 96%,95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chain frameworkregions of SEQ ID NO: 10, and the antibody light chain comprises lightchain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the framework regions of SEQ ID NO: 11.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antihbody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 58), CDR2(SEQ ID NO: 57), and CDR3 (SEQ ID NO: 56) of SEQ ID NO: 12, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 61), CDR2 (SEQ ID NO: 60), and CDR3 (SEQ ID NO: 59) of SEQID NO: 13. In an additional aspect the heavy chain comprises a heavychain variable region comprising SEQ ID NO: 12, and the light chaincomprises a light chain variable region comprising SEQ ID NO: 13. In afurther aspect, heavy chain variable region is 99%, 98%, 97%, 96%, 95%,94%, 93%, 92%, 91%, or 90% identical to SEQ ID NO: 12, and the lightchain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or90% identical to SEQ ID NO: 13.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 58, a heavychain CDR2 region comprising SEQ ID NO: 57, and heavy chain CDR3 regioncomprising SEQ ID NO: 56; and (b) light chain framework regions, a lightchain CDR1 region comprising SEQ ID NO: 61, a light chain CDR2 regioncomprising SEQ ID NO: 60, and a light chain CDR3 region comprising SEQID NO: 59. In certain aspects, the antibody heavy chain comprises heavychain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the heavy chain framework regions of SEQ ID NO:12, and the antibody light chain comprises light chain framework regionsthat are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identicalto the framework regions of SEQ ID NO: 13.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 64), CDR2(SEQ ID NO: 63), and CDR3 (SEQ II) NO: 62) of SEQ ID NO: 14, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 67), CDR2 (SEQ ID NO: 66), and CDR3 (SEQ ID NO: 65) of SEQID NO: 15. In an additional aspect the heavy chain comprises a heavychain variable region comprising SEQ ID NO: 14, and the light chaincomprises a light chain variable region comprising SEQ ID NO: 15. In afurther aspect, heavy chain variable region is 99%, 98%, 97%, 96%, 95%,94%, 93%, 92%, 91%, or 90% identical to SEQ ID NO: 14, and the lightchain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or90% identical to SEQ ID NO: 15.

In an additional aspect, disclosed herein is an isolated monoclonalantibody that binds specifically to PAI-1, comprising: (a) heavy chainframework regions, a heavy chain CDR1 region comprising SEQ ID NO: 64, aheavy chain CDR2 region comprising SEQ ID NO: 63, and a heavy chain CDR3region comprising SEQ ID NO: 62: and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 67, a light chain CDR2region comprising SEQ ID NO: 66, and a light chain CDR3 regioncomprising SEQ ID NO: 65. In certain aspects, the antibody heavy chaincomprises heavy chain framework regions that are 99%, 98%, 97%, 96%,95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chain frameworkregions of SEQ ID NO: 14, and the antibody light chain comprises lightchain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the framework regions of SEQ ID NO: 15.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 70), CDR2(SEQ ID NO: 69), and CDR3 (SEQ ID NO: 68) of SEQ ID NO: 16, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 73), CDR2 (SEQ ID NO: 72), and CDR3 (SEQ ID NO: 71) of SEQID NO: 17.

In an additional aspect the heavy chain comprises a heavy chain variableregion comprising SEQ ID NO: 16, and the light chain comprises a lightchain variable region comprising SEQ ID NO: 17. In a further aspect,heavy chain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to SEQ ID NO: 16, and the light chain variableregion is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identicalto SEQ ID NO: 17.

In an additional aspect, disclosed herein is an isolated monoclonalantibody that binds specifically to PAI-1, comprising: (a) heavy chainframework regions, a heavy chain CDR1 region comprising SEQ ID NO: 70, aheavy chain CDR2 region comprising SEQ ID NO: 69, and a heavy chain CDR3region comprising SEQ ID NO: 68; and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 73, a light chain CDR2region comprising SEQ ID NO: 72, and a light chain CDR3 regioncomprising SEQ ID NO: 71. In certain aspects, the antibody heavy chaincomprises heavy chain framework regions that are 99%, 98%, 97%, 96%,95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chain frameworkregions of SEQ ID NO: 16, and the antibody light chain comprises lightchain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the framework regions of SEQ ID NO: 17.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to human Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 46), CDR2(SEQ ID NO: 45), and CDR3 (SEQ ID NO: 44) of SEQ ID NO: 80, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 49), CDR2 (SEQ ID NO: 48), and CDR3 (SEQ ID NO: 47) of SEQID NO: 81.

In an additional aspect the heavy chain comprises a heavy chain variableregion comprising SEQ ID NO: 80, and the light chain comprises a lightchain variable region comprising SEQ ID NO: 81. In a further aspect,heavy chain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to SEQ ID NO: 80, and the light chain variableregion is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identicalto SEQ ID NO: 81.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 46, a heavychain CDR2 region comprising SEQ ID NO: 45, and a heavy chain CDR3region comprising SEQ ID NO: 44; and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 49, a light chain CDR2region comprising SEQ ID NO: 48, and a light chain CDR3 regioncomprising SEQ ID NO: 47. In certain aspects, the antibody heavy chaincomprises heavy chain framework regions that are 99%, 98%, 97%, 96%,95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chain frameworkregions of SEQ ID NO: 80, and the antibody light chain comprises lightchain framework regions that are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to the framework regions of SEQ ID NO: 81.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to Plasminogen Activator Inhibitor type-1(PAI-1), wherein the antibody comprises a heavy chain variable region,said heavy chain variable region comprising CDR1 (SEQ ID NO: 76), CDR2(SEQ ID NO: 75), and CDR3 (SEQ ID NO: 74) of SEQ ID NO: 18, and a lightchain variable region, said light chain variable region comprising CDR1(SEQ ID NO: 79), CDR2 (SEQ ID NO: 78), and CDR3 (SEQ ID NO: 77) of SEQID 19. In an additional aspect the heavy chain comprises a heavy chainvariable region comprising SEQ ID NO: 18, and the light chain comprisesa light chain variable region comprising SEQ ID NO: 19. In a furtheraspect, heavy chain variable region is 99%, 98%, 97%, 96%, 95%, 94%,93%, 92%, 91%, or 90% identical to SEQ ID NO: 18, and the light chainvariable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90%identical to SEQ ID NO: 19.

An isolated monoclonal antibody that binds specifically to PAI-1,comprising: (a) heavy chain framework regions, a heavy chain CDR1 regioncomprising SEQ ID NO: 76, heavy chain CDR2 region comprising SEQ ID NO:75, and a heavy chain CDR3 region comprising SEQ ID NO: 74; and (h)light chain framework regions, a light chain CDR1 region comprising SEQID NO: 79, a light chain CDR2 region comprising SEQ ID NO: 78, and alight chain CDR3 region comprising SEQ ID NO: 77. In certain aspects,the antibody heavy chain comprises heavy chain framework regions thatare 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identical to theheavy chain framework regions of SEQ ID NO: 18, and the antibody lightchain comprises light chain framework regions that are 99%, 98%, 97%,96%, 95%, 94%, 93%, 92%, 91%, or 90%/u identical to the frameworkregions of SEQ ID NO: 19.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR region comprising SEQ ID NO: 33, heavy chainCDR2 region comprising SEQ ID NO: 146, and a heavy chain CDR3 regioncomprising SEQ ID NO: 32; and (b) light chain framework regions, a lightchain CDR1 region comprising SEQ ID NO: 37, a light chain CDR2 regioncomprising SEQ ID NO: 145, and a light chain CDR3 region comprising SEQID NO: 35.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 147, heavychain CDR2 region comprising SEQ ID NO: 33, and a heavy chain CDR3region comprising SEQ ID NO: 32; and (h) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 37, a light chain CDR2region comprising SEQ ID NO: 36, and a light chain CDR3 regioncomprising SEQ ID NO: 35.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 147, heavychain CDR2 region comprising SEQ ID NO: 33, and a heavy chain CDR3region comprising SEQ ID NO: 32: and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 37, a light chain CDR2region comprising SEQ ID NO: 145, and a light chain CDR3 regioncomprising SEQ ID NO: 35.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 146, heavychain CDR2 region comprising SEQ ID NO: 33, and a heavy chain CDR3region comprising SEQ ID NO: 32; and (b) light chain framework regions,a light chain CDR1 region comprising SEQ ID NO: 37, a light chain CDR2region comprising SEQ ID NO: 145, and a light chain CDR3 regioncomprising SEQ ID NO: 35.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 34, heavy chainCDR2 region comprising SEQ ID NO: 33, and a heavy chain CDR3 regioncomprising SEQ ID NO: 32; and (b) light chain framework regions, a lightchain CDR1 region comprising SEQ ID NO: 37, a light chain CDR2 regioncomprising SEQ ID NO: 145, and a light chain CDR3 region comprising SEQID NO: 35.

In an additional aspect, disclosed herein is an isolated monoclonalantibody that binds to essentially the same epitope on PAI-1 as anisolated monoclonal antibody, comprising a heavy chain variable region,wherein the heavy chain variable region comprises CDR1 (SEQ ID NO: 34),CDR2 (SEQ ID NO: 33), and CDR3 (SEQ ID NO: 32) of SEQ ID NO: 6, and alight chain variable region, wherein the light chain variable regioncomprises CDR1 (SEQ ID NO: 37), CDR2 (SEQ ID NO: 36), and CDR3 (SEQ IDNO: 35) of SEQ ID NO: 7.

In a certain aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, comprising: (a) heavy chain frameworkregions, a heavy chain CDR1 region comprising SEQ ID NO: 76, heavy chainCDR2 region comprising SEQ ID NO: 75, and a heavy chain CDR3 regioncomprising SEQ ID NO: 74: and (b) light chain framework regions, a lightchain CDR1 region comprising SEQ ID NO: 79, a light chain CDR2 regioncomprising SEQ ID NO: 78, and a light chain CDR3 region comprising SEQID NO: 77.

In one aspect, disclosed herein is a humanized monoclonal antibody thatbinds specifically to human PAI-1, wherein the antibody comprises: (a) aheavy chain having a heavy chain variable region comprising SEQ ID NO:82, or an antigen-binding fragment thereof, and a light chain having alight chain variable region comprising SEQ ID NO: 91, or anantigen-binding fragment thereof; (b)

a heavy chain having a heavy chain variable region comprising SEQ ID NO:83, or an antigen-binding fragment thereof, and a light chain having alight chain variable region comprising SEQ ID NO: 92, or anantigen-binding fragment thereof, (c) a heavy chain having a heavy chainvariable region comprising SEQ ID NO: 84, or an antigen-binding fragmentthereof, and a light chain having a light chain variable regioncomprising SEQ ID NO: 93, or an antigen-binding fragment thereof. (d) aheavy chain having a heavy chain variable region comprising SEQ ID NO:85, or an antigen-binding fragment thereof, and a light chain having alight chain variable region comprising SEQ ID NO: 91, or anantigen-binding fragment thereof: (c) a heavy chain having a heavy chainvariable region comprising SEQ ID NO: 85, or an antigen-binding fragmentthereof, and a light chain having a light chain variable regioncomprising SEQ ID NO: 93, or an antigen-binding fragment thereof: (1) aheavy chain having a heavy chain variable region comprising SEQ ID NO:86, or an antigen-binding fragment thereof, and a light chain having alight chain variable region comprising SEQ ID NO: 94, or anantigen-binding fragment thereof: (g) a heavy chain having a heavy chainvariable region comprising SEQ ID NO: 87, or an antigen-binding fragmentthereof, and a light chain having a light chain variable regioncomprising SEQ ID NO: 95, or an antigen-binding fragment thereof; (h) aheavy chain having a heavy chain variable region comprising SEQ ID NO:88, or an antigen-binding fragment thereof, and a light chain having alight chain variable region comprising SEQ ID NO: 96, or anantigen-binding fragment thereof; (i) a heavy chain having a heavy chainvariable region comprising SEQ ID NO: 89, or an antigen-binding fragmentthereof, and a light chain having a light chain variable regioncomprising SEQ ID NO: 97, or an antigen-binding fragment thereof; (j) aheavy chain having a heavy chain variable region comprising SEQ ID NO:90, or an antigen-binding fragment thereof, and a light chain having alight chain variable region comprising SEQ ID NO: 98, or anantigen-binding fragment thereof; (k) a heavy chain having a heavy chainvariable region comprising SEQ ID NO: 86, or an antigen-binding fragmentthereof, and a light chain having a light chain variable regioncomprising SEQ ID NO: 93, or an antigen-binding fragment thereof; (1) aheavy chain having a heavy chain variable region comprising SEQ ID NO:86, or an antigen-binding fragment thereof, and a light chain having alight chain variable region comprising SEQ ID NO: 95, or anantigen-binding fragment thereof; (m) a heavy chain having a heavy chainvariable region comprising SEQ ID NO: 89, or an antigen-binding fragmentthereof, and a light chain having a light chain variable regioncomprising SEQ ID NO: 93, or an antigen-binding fragment thereof; or (n)a heavy chain having a heavy chain variable region comprising SEQ ID NO:89, or an antigen-binding fragment thereof, and a light chain having alight chain variable region comprising SEQ ID NO: 95, or anantigen-binding fragment thereof. In a further aspect, the humanizedheavy chain variable region is 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%,91%, or 90% identical to any of the previously disclosed human heavychain variable regions, and the humanized light chain variable region is99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identical to any ofthe previously disclosed human light chain variable regions.

In one aspect, disclosed herein is an isolated monoclonal antibody thatbinds specifically to PAI-1 comprising: (a) a heavy chain frameworkregion and a heavy chain variable region comprising SEQ ID NO: 86, and(b) a light chain framework region and a light chain variable regioncomprising SEQ ID NO: 93. In certain aspects, the isolated monoclonalheavy chain comprises heavy chain framework regions that are 99%, 98%,97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identical to the heavy chainframework regions of SEQ ID NO: 86, and the isolated monoclonal antibodylight chain comprises light chain framework regions that are 99%, 98%,97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identical to the frameworkregions of SEQ ID NO: 93. In certain other aspects, the isolatedmonoclonal antibody heavy chain comprises heavy chain framework regionsthat are 95% identical to the heavy chain framework regions of SEQ IDNO: 86, and the isolated monoclonal antibody light chain comprises lightchain framework regions that are 95% identical to the framework regionsof SEQ ID NO: 93.

In another aspect, disclosed herein is a humanized monoclonal antibodythat binds specifically to human PAI-1, wherein the antibody comprises aheavy chain having a heavy chain variable region comprising SEQ ID NO:154, or an antigen-binding fragment thereof; and a light chain having alight chain variable region comprising SEQ ID NO: 153, or anantigen-binding fragment thereof. In another aspect, disclosed herein isa humanized monoclonal antibody that binds specifically to human PAI-1,wherein the antibody comprises a heavy chain having a heavy chainvariable region comprising SEQ ID NO: 155, or an antigen-bindingfragment thereof, and a light chain having a light chain variable regioncomprising SEQ ID NO: 153, or an antigen-binding fragment thereof. In afurther aspect, the humanized heavy chain variable region is 99%, 98%,97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identical to any of thepreviously disclosed human heavy chain variable regions, and thehumanized light chain variable region is 99%, 98%, 97%, 96%, 95%, 94%,93%, 92%, 91%, or 90% identical to any of the previously disclosed humanlight chain variable regions.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, wherein the antibody binds apolypeptide comprising SEQ ID NO: 158. In another embodiment, theisolate monoclonal antibody binds a fragment of a polypeptide comprisingSEQ ID NO: 158. In yet another embodiment, the isolated monoclonalantibody that binds specifically to PAI-1 binds a polypeptide comprisingSEQ ID NO: 156 and/or SEQ ID NO: 158. In another embodiment, theisolated monoclonal antibody that binds specifically to PAI-1 binds apolypeptide comprising SEQ ID NO: 156, SEQ ID NO: 158, and/or SEQ ID NO:157. In still another embodiment, the isolated monoclonal antibody thatbinds specifically to PAI-1 comprises specific binding affinity forresidues 160, 262, 296-297, 300-307, and/or 310-316 of SEQ ID NO: 1. Incertain embodiments, the isolated monoclonal antibody disclosed hereininteracts with at least residues 311, 312, and 313 (D-Q-E) of SEQ IDNO: 1. In certain embodiments, the PAI-1 bound by the antibody is humanPAI-1. In other embodiments, the PAI-1 bound by the antibody is theactive form of human PAI-1.

In other embodiments, the isolated monoclonal antibody that bindsspecifically to PAI-1 disclosed herein binds a polypeptide comprisingSEQ ID NO: 161. In still other embodiments, the isolated monoclonalantibody binds a polypeptide comprising SEQ ID NO: 159 and/or SEQ ID NO:161. In still other embodiments, the isolated monoclonal antibody bindsa polypeptide comprising SEQ ID NO: 159, SEQ ID NO: 160, and/or SEQ IDNO: 161. In still another embodiment, the isolated monoclonal antibodythat binds specifically to PAI-1 comprises specific binding affinity forresidues 44-64 and/or residues 307-321 of cyno-PAI-1 (SEQ ID NO: 162).In certain embodiments, the PAI-1 hound by the antibody is cyno-PAT-1.In other embodiments, the PAI-1 bound by the antibody is the latent formof cyno-PAI-1.

In a further aspect, disclosed herein is an isolated monoclonal antibodythat competitively inhibits binding of any of the disclosed antibodiesto PAI-1. In an embodiment, disclosed herein is an isolated monoclonalantibody that competes for binding and/or competitively inhibits bindingwith any of the isolated monoclonal antibodies disclosed herein. Incertain embodiments, the isolated monoclonal antibody competes orcompetitively inhibits binding to human PAI-1. In certain embodiments,the isolated monoclonal antibody competes or competitively inhibitsbinding to a polypeptide comprising SEQ ID NO: 156, SEQ ID NO: 157,and/or SEQ ID NO: 158. In another embodiment, the isolated monoclonalantibody competes or competitively inhibits binding to a polypeptidecomprising SEQ ID NO: 159, SEQ ID NO: 160, and/or SEQ ID NO: 161. In anembodiment, the isolated antibody competes for binding to a polypeptidecomprising SEQ ID NO: 156, 157, and/or 158 with an isolated monoclonalantibody comprising (a) heavy chain framework regions, a heavy chainCDR1 region comprising SEQ ID NO: 34, heavy chain CDR2 region comprisingSEQ ID NO: 33, and a heavy chain CDR3 region comprising SEQ ID NO: 32;and (b) light chain framework regions, a light chain CDR1 regioncomprising SEQ ID NO: 37, a light chain CDR2 region comprising SEQ IDNO: 145, and a light chain CDR3 region comprising SEQ ID NO: 35.

In another aspect, disclosed herein are nucleotides encoding any of theisolated monoclonal antibodies disclosed herein.

In one aspect, disclosed herein is a method of treating a conditioncaused by increased expression of PAI-1 or increased sensitivity toPAI-1 comprising administering to a patient or other subject orally,parenterally by a solution for injection, by inhalation, or topically apharmaceutically effective amount of a PAI-1 antibody.

In one aspect, disclosed herein is a method restoring plasnmingeneration comprising administering to a patient or other subject inneed thereof orally, parenterally by a solution for injection, byinhalation, or topically a pharmaceutically effective amount of a PAI-1antibody. Parenteral administration disclosed herein includesintravenous, drip, intraarterial intraperitoneal, intramuscular,subcutaneous, rectal or vaginal, intravenous, intraarterial,subcutaneous, and intramuscular forms of parenteral administration. Insome embodiments, the administration to a patient or other subjectcomprises multiple administrations. In another aspect, the method ofrestoring plasmin generation facilitates therapeutic treatment of acondition comprising increased levels of fibrotic tissue. In someaspects, the condition is characterized by fibrosis. In some aspects,the condition is fibrosis, skin fibrosis, systemic sclerosis, lungfibrosis, idiopathic pulmonary fibrosis, interstitial lung disease, andchronic lung disease. In other aspects, the plasmin generationfacilitates therapeutic treatment of liver fibrosis, kidney fibrosis,including chronic kidney disease, thrombosis, venous and arterialthrombosis, deep vein thrombosis, peripheral limb ischemia, disseminatedintravascular coagulation thrombosis, acute ischemic stroke with andwithout thrombolysis, or stent restenosis.

In another aspect, disclosed herein is the use of a pharmaceuticallyeffective amount of a PAI-1 antibody for the manufacture of a medicamentfor treating a condition caused by increased expression of PAI-1 orincreased sensitivity to PAI-1 comprising administering to a patient orother subject orally, parenterally by a solution for injection, byinhalation, or topically.

In one aspect, the medicament is for treating a condition comprisingincreased levels of fibrotic tissue. In some aspects, the condition ischaracterized by fibrosis. In some aspects, the condition is fibrosis,skin fibrosis, systemic sclerosis, lung fibrosis, idiopathic pulmonaryfibrosis, interstitial lung disease, and chronic lung disease. In otheraspects, the medicament is for treating a condition comprising liverfibrosis, kidney fibrosis, including chronic kidney disease, thrombosis,venous and arterial thrombosis, deep vein thrombosis, peripheral limbischemia, disseminated intravascular coagulation thrombosis, acuteischemic stroke with and without thrombolysis, or stent restenosis.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, wherein the antibody inhibits lungfibrosis. In certain embodiments, the antibody inhibits fibrosis in thelung of a subject. In certain embodiments, the antibody inhibitsfibrosis in the lung of a subject with idiopathic pulmonary fibrosis(IPF). In some embodiments, the isolated monoclonal antibody disclosedherein induces an increase in fibrin degradation in a subject. Incertain embodiments, the antibody increases fibrin degradation in theplasma of the subject. In some other embodiments, the isolatedmonoclonal antibody disclosed herein inhibits collagen accumulation inthe lung of a subject. In some embodiments, the subject has IPF. In someother embodiments, the isolated monoclonal antibody disclosed hereinincreases D-dimer levels in the bronchoalveolar lavage fluid (BALF) of asubject. In some embodiments, the subject has IPF. In some otherembodiments, the isolated monoclonal antibody disclosed herein bindsspecifically to PAI-1, wherein the antibody inhibits the increase inlung weight due to fibrosis in a subject. In one embodiment, the subjecthas IPF.

In another aspect, disclosed herein is the use of a pharmaceuticallyeffective amount of a PAI-1 antibody for the manufacture of a medicamentfor treating a condition caused by increased expression of PAI-1 orincreased sensitivity to PAI-1 comprising administering to a patientorally, parenterally by a solution for injection, by inhalation, ortopically, wherein the condition is idiopathic pulmonary fibrosis.

In another aspect, disclosed herein is a method restoring plasmingeneration comprising administering to a to a patient or other subjectthereof orally, parenterally by a solution for injection, by inhalation,or topically a pharmaceutically effective amount of a PAI-1 antibody,wherein the plasmin generation facilitates therapeutic treatment ofidiopathic pulmonary fibrosis.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, wherein the antibody restoresfibrinolytic activity in a subject. In certain embodiments, the antibodyrestores fibrinolytic activity in a subject with acute ischemic stroke.The acute ischemic stroke can be either with or without thrombolysis. Insome embodiments, the isolated monoclonal antibody restores clot lysis.In certain embodiments, the antibody restores in vitro clot lysis. Instill other embodiments, the antibody restores in vitro clot lysis withan IC₅₀ of about 2 nM.

In other aspects, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, wherein the antibody restores fibrinbreakdown in a subject. In some embodiments, the subject has acuteischemic stroke.

In another aspect, disclosed herein is the use of a pharmaceuticallyeffective amount of a PAI-1 antibody for the manufacture of a medicamentfor treating a condition caused by increased expression of PAI-1 orincreased sensitivity to PAI-1 comprising administering to a patientorally, parenterally by a solution for injection, by inhalation, ortopically, wherein the condition is acute ischemic stroke with andwithout thrombolysis.

In another aspect, disclosed herein is a method restoring plasmingeneration comprising administering to a patient or other subject inneed thereof orally, parenterally by a solution for injection, byinhalation, or topically a pharmaceutically effective amount of a PAI-1antibody, wherein the plasmin generation facilitates therapeutictreatment of acute ischemic stroke with and without thrombolysis.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, wherein the antibody inhibitsformation of adhesions in a subject. In some embodiments, the adhesionformation is following surgery or injury to the subject. In someembodiments, the adhesion formation in the subject is abdominal. Inother embodiments, the adhesion formation occurs in the shoulder,pelvis, heart, spine, hand, and other body regions of the subject.

In another aspect, disclosed herein is the use of a pharmaceuticallyeffective amount of a PAI-1 antibody for the manufacture of a medicamentfor treating or preventing a condition caused by increased expression ofPAI-1 or increased sensitivity to PAI-1 comprising administering to apatient orally, parenterally by a solution for injection, by inhalation,or topically, wherein the condition is abdominal adhesion formation.

In another aspect, disclosed herein is a method of restoring plasmingeneration comprising administering to a to a patient or other subjectin need thereof orally, parenterally by a solution for injection, byinhalation, or topically a pharmaceutically effective amount of a PAI-1antibody, wherein the plasmin generation facilitates therapeutictreatment or prevention of adhesion formation. In some embodiments, theadhesion formation in the subject is abdominal.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds to a PAI-1/vitronectin complex. In another aspect, disclosedherein is an isolated monoclonal antibody that neutralizes PAI-1activity by inducing PAI-1 substrate conformation. In an embodiment, theantibody restores or is capable of restoring plasmin generation. Inanother embodiment, the isolated monoclonal antibody induces or iscapable of inducing fibronectin degradation. In yet another embodiment,the isolated monoclonal antibody induces or is capable of inducingmatrix metalloproteinases (MMP) activation.

In another aspect, the isolated monoclonal antibody disclosed herein isan antibody fragment. In some embodiments, the antibody is asingle-chain Fv antibody. In other embodiments, the heavy chain andlight chain are connected by a flexible linker to form a single-chainantibody. In other embodiments, the antibody is a Fab, Fab′, or (Fab′)₂antibody.

In another aspect, disclosed herein is an isolated monoclonal antibodythat binds specifically to PAI-1, wherein the antibody is a crystallizedantibody. In an embodiment, disclosed herein is an isolated crystalcomprising the Fab′ fragment of monoclonal antibody A44, wherein theFab′ fragment consists of light chain sequence SEQ ID NO:7 and heavychain sequence SEQ ID NO:6. In another embodiment, disclosed herein isan isolated crystal comprising a Fab′ fragment comprising light chainsequence SEQ ID NO:93 and heavy chain sequence SEQ ID NO:86. In anembodiment, the isolated crystal comprises assymetric unit celldimensions a=105 Å, b=152 Å and c=298 Å. In an embodiment, the isolatedcrystal belongs to P212121 space group. In another embodiment, theisolated crystal comprises a 3.3 Å resolution of x-ray diffraction. Inan embodiment, the isolated crystal retains the biological activity ofthe crystallized antibody. In some embodiments, the isolated crystal hasa greater half life in vivo than the soluble counterpart of thecrystallized antibody.

In one aspect, disclosed herein is a pharmaceutical compositioncomprising: (a) the crystallized antibody that binds specifically toPAI-1 and (b) at least one pharmaceutical excipient which embeds orencapsulates the crystal.

In another aspect, disclosed herein is a pharmaceutical compositioncomprising a pharmaceutically acceptable carrier and a therapeuticallyeffective amount of any of the antibodies disclosed herein.

In one aspect, disclosed herein is a method of generating an antibodyagainst PAI-1 comprising immunizing a mammal with a complex composed ofPAI-1 or a fragment thereof, and vitronectin.

In another aspect, disclosed herein is a method of screening a PAI-1antibody in an ELISA for its ability to block PAI-1's function as a tPAactivity inhibitor, comprising the steps of: (a) binding PAI-1 to anELISA plate; (b) incubating the ELISA plate with the PAI-1 antibody; (c)incubating the ELISA plate with tPA; (d) incubating the ELISA plate withlabeled anti-tPA antibody; and (e) measuring the OD₄₀₅ emitted by thelabeled anti-tPA antibody; wherein a positive readout indicates that thePAI-1 antibody binds to PAI-1 but does not block formation of thecovalent bond between PAI-1 and tPA, and a negative readout indicatesthat the PAI-1 antibody blocks tPA interaction with PAI-1.

In another aspect, disclosed herein is a method of screening hybridomas.In certain embodiments, the method of screening comprises a reversescreening method using anti-mouse immobilized anti-PAI-1 antibodies. Inother embodiments, the method of screening comprises or a forwardscreening assay using free PAI-1 as a ligand or against immobilizedvitronectin. In certain embodiments, the method is applied to determinethe affinity of an antibody for a PAI-1/vitronectin complex. In someembodiments, the method comprises: immobilizing vitronectin to asurface; contacting PA-1 with the vitronectin immobilized to thesurface, thereby forming a complex; contacting the surface comprisingthe complex with the antibody; separating the antibody bound to thecomplex from unbound antibody; detecting the antibody bound to thecomplex, and analyzing the levels of antibody bound to the complex todetermine the affinity of the antibody for the complex.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic representation of the mechanisms betweenPAI-1 and the serine proteases tissue-type plasminogen activator (tPA)and urokinase-type plasminogen activator (uPA). PAI-1 exhibitsstructural flexibility and can occur in a latent conformation or anactive conformation when it is bound to vitronectin (Vn). The RCL regionof PA-1 bears the bait peptide bond (also called P1-P1′) that is thecleavage site by the serine protease. A Michaelis complex with tPA oruPA forms first, then the catalytic triad reacts with the bait peptidebond to form an acyl-enzyme complex that, after cleavage of the P1-P′1peptide bond, induces strong conformation changes. Acyl enzyme is alabile complex formed by covalent bond between the serine residue (blacktriangle) from catalytic triad from serine protease (tPA) and amino-acidfrom the substrate (black circle) that undergoes further hydrolysis. Theconformational changes causes insertion of the cleaved RCL into aS-strand with the protease staying covalently hound as an acyl enzymewith PAI-1. Under non physiological circumstance, hydrolysis of thisacyl-enzyme complex may induce release of the cleaved PAI-1 and freeactive protease.

FIG. 2 depicts a typical standard curve for antibody titration in thebinding ELISA as described in Example 2. The antibodies 31C9, 33B8 and33H1 were positive controls and IgG1 was as a negative control.

FIG. 3 depicts a representation curve for a functional ELISA to selectantibodies that block the interaction of PAI-1 with tPA as described inExample 4. The antibody 33H1 is a positive control, IgG1 is a negativecontrol and A44 was identified as a positive antibody clone.

FIG. 4 depicts neutralization of human PAI-1 blocking activity of tPA byA44 and commercially available antibodies (33B8 and 33H1) in thechromogenic assay described in Example 4.

FIG. 5 depicts neutralization of human PAI-1 blocking activity of tPA bya selection of antibodies produced from different fusions (see Example4).

FIG. 6 depicts human PAI-1 and its orthologs block human tPA activity inchromogenic assay with the similar potency.

FIG. 7 depicts neutralization of cynomolgous (cyno) and mouse PAI-1blocking activity of human tPA by A44 and 33B8 (commercially available)antibodies in the chromogenic assay described m Example 4.

FIG. 8 depicts SDS-Pagc analysis of the mechanism of action forantibodies 33H8 (converts PAI-1 from active to latent confirmation),33H1 (converts PAI-1 from active to substrate conformation) and A44 toblock the interaction of PAI-1 with tPA. Lane 1: molecular weightstandards; Lane 2: PAI-1 only: Lane 3: tPA only; Lane 4: PAI-1 in thepresence of tPA; Lane 5: 33B8+PAI-1+tPA: Lane 6: 33H1+PAI-1+tPA; Lane 7:A44+PAI-1+tPA; Lane 8: mAb is an isotype control antibody.

FIG. 9 depicts SDS-Page analysis of the mechanism of action forantibodies 33H8 (converts PAI-1 from active to latent confirmation),33H1 (converts PAI-1 from active to substrate conformation) andantibodies developed from fusions C26, E16 and E21 to block theinteraction of PAI-1 with tPA. Lane 1: molecular weight standards; Lane2: PAI-1 only; Lane 3: tPA only; Lane 4: PAI-1 in the presence of tPA;Lane 5: 33B8+PAI-1+tPA; Lane 6: 33H1+PAI-1+tPA; Lane 7: C26+PAI-1+tPA;Lane 8: E16+PAI-1+tPA; Lane 9: E21+PAI-1+tPA; Lane 10: mAb is an Isotypecontrol antibody.

FIG. 10 depicts SDS-Page analysis of the mechanism of action forantibodies 33H8 (converts PAI-1 from active to latent confirmation),33H1 (converts PAI-1 from active to substrate conformation) andantibodies developed from fusions A39, B109 and C45 to block theinteraction of PAI-1 with tPA. Lane 1: molecular weight standards; Lane2: PAI-1 only; Lane 3: tPA only; Lane 4: PAI-1 in the presence of tPA;Lane 5: 33B8+PAI-1+tPA; Lane 6: 33H1+PAI-1+tPA; Lane 7: A39+PAI-1+tPA;Lane 8: B109+PAI-1+tPA; Lane 9: C45+PAI-1+tPA; Lane 10: mAb is anisotype control antibody.

FIG. 11 depicts the alignment of the light chain of the following murineantibodies: A105 (SEQ ID NO: 3), A39 (SEQ ID NO: 5), A44 (SEQ ID NO: 7),A71 (SEQ ID NO: 9), A75 (SEQ ID NO: 81), B109 (SEQ ID NO: 11), B28 (SEQID NO: 13), C45 (SEQ ID NO: 15), E16 (SEQ ID NO: 17), and E21 (SEQ IDNO: 19). CDRs are highlighted in bold.

FIG. 12 depicts the alignment of the heavy chain of the following murineantibodies: A105 (SEQ ID NO: 2). A39 (SEQ ID NO: 4), A44 (SEQ ID NO: 6),A71 (SEQ ID NO: 8), A75 (SEQ ID NO: 80), B109 (SEQ ID NO: 10), B28 (SEQID NO: 12), C45 (SEQ ID NO: 14), E16 (SEQ ID NO: 16), and E21 (SEQ IDNO: 18). CDRs, as defined by IMGT, are highlighted in bold.

FIG. 13 depicts the alignment of murine A44 light chain (SEQ ID NO: 7)with vk1 (SEQ ID NO: 101) and vlambda3 (SEQ ID NO: 102).

FIG. 14 depicts the alignment of murine A44 heavy chain (SEQ ID NO: 6)with vh2 (SEQ ID NO: 103) and vh4 (SEQ ID NO: 104).

FIG. 15 depicts clone A44 humanization VL with all constructs aligned.All aligned sequences (SEQ ID NOs: 91-98) are further described below inTable 25. Black boxes represent CDR domains. Highlighted residues vary msequence from the residue directly above in the alignment. Residuenumbering is as described by IMGT.

FIG. 16 depicts clone A44 humanization VH with all constructs aligned.All aligned sequences (SEQ ID NOs: 82-90) are further described below inTable 25. Black boxes represent CDR domains. Highlighted residues varyin sequence from the residue directly above in the alignment. Residuenumbering is as described by IMGT.

FIG. 17 depicts percent inhibition of PAI-1 activity was plotted as afunction of mAb concentration and IC50 was determined Imax using Biostatspeed software.

FIG. 18 depicts purification of homogeneity recombinant 6-His tagged FabA44.

FIG. 19 depicts SPR analysis with Biacore 2000 using single kineticanalysis of human PAI-1 glycosylated binding to immobilized APGantibody. A sensogram firm single-cycle kinetic is shown in grey. Fitmodel is shown in black.

FIG. 20 depicts human plasma PAI-1 neutralization by APG, APGv2, andAPGv4 antibodies as determined by UK-PAI-1 complex formation detectionby ELISA. Percent inhibition of PAI-1 activity was plotted as a functionof concentration of APG, APGv2, or APGv4 antibodies.

FIG. 21 depicts restoration of human plasma clot lysis by A44V11 (1, 3or 10 nM) in the presence of tPA 1 nM and PAI-1 3 nM as detected byturbidimetry kinetic measurement by absorbance reading at 340 nm as afunction of time (min).

FIG. 22 depicts absence of restoration of human plasma clot lysis byhuman IgG1 negative controle (1, 3 or 10 nM) in the presence of tPA 1 nMand PAI-1 3 nM as detected by absorbance at 340 nm as a function of time(min).

FIG. 23 depicts restoration of human plasma clot lysis by A44V11 orhuman IgG1 isotype negative control at various concentrations.

FIG. 24 depicts restoration of human plasma clot lysis by APG, APGV2 orAPGV4 at 3 nM in the presence of tPA 1 nM and PAI-1 3 nM as detected byabsorbance at 340 nm as a function of time (min).

FIG. 25 depicts restoration of human plasma clot lysis by APG variant 2and 4 at various concentrations.

FIG. 26 depicts immunoblot anti-PAI-1 on human LL29 myofibroblastsupernatants at 48H after treatment by A44V11 or IgG isotype control mAbat 50 nM and TGFβ 5 ng/ml.

FIG. 27 depicts generic MMP activity in human primary lung fibroblastsafter cell treatment for 48 hr with PBS (control), plasminogen (Pg),A44v11 and plasminogen (A+Pg) or negative human IgG and plasminogen(Neg+Pg).

FIG. 28 depicts human active PAI-1 level in broncho-alveolar lavagefluid (BALF) (A) and m lung lysate (B) from bleomycin treated mice atday 7 and day 9 following treatment at day 4 with A44 or IgG1 at 10mg/kg or PBS by i.p. administration. Active PAI-1 determined by ELISA(#HPAIKT Molecular Innovation). Percentage of inhibition were calculatedby dividing the difference between A44 bleo and IgG bleo by thedifference between IgG bleo and untreated (PBS) mice group.

FIG. 29 depicts mouse D-Dimer level in BALF from bleomycin treated miceat day7 and day9 following treatment at day4 with A44 or IgG1 at 10mg/kg or PBS by i.p. administration as determined by ELISA (AsseraclromD-Di, Diagnostica Stago). Fold increase in D-dimer induced by A44 incomparison to IgG are indicated.

FIG. 30 depicts right lung weight from transgenic humanized mice 21 daysafter either saline or bleomycin treatment followed by PBS (vehicle),IgG1 or A44 10 mg/kg i.p. administration from day4 to day20 every 3days.

FIG. 31 depicts hydroxyproline lung content in transgenic humanized mice21 days after either saline or bleomycin treatment followed by PBS(vehicle), IgG1 or A44 10 mg/kg i.p. administration from day4 to day20every 3 days.

FIG. 32 depicts active PAI-1 level in plasma from monkeys treated byA44V11 (A) mAb (n=5) or with IgG1 isotype control (B) (n=4) (5 mg/kg ip)24 hours before LPS challenge (100 ug/kg iv). Blood samples wereharvested at the indicated time point and active PAI-1 levels weredetermined in plasma using the ELISA (# HPAIKT from MolecularInnovation).

FIG. 33 depicts active PAI-1 level in liver biopsy from monkeys treatedby A44V11 (A) mAb (n=5) or with IgG1 isotype control (B) (n=4) (5 mg/kgip) 24 hours before LPS challenge (100 ug/kg iv). Liver biopsies wereharvested in anesthetized monkeys at the indicated time point and activePAI-1 levels were determined in lysates using the ELISA (# HPAIKT fromMolecular Innovation).

FIG. 34 depicts D-dimer level m plasma from monkeys treated by A44V11(A) mAb (n=5) or with IgG1 isotype control (B) (n=4) (5 mg/kg ip) 24hours before LPS challenge (100 ug/kg iv). Blood samples were harvestedat the indicated time point and D-dimer levels were determined in plasmausing the ELISA.

FIG. 35 depicts Plasmin-α2 Antiplasmin (PAP) complexes level in plasmafrom monkeys treated by A44V11 (A) mAb (n=5) or with IgG1 isotypecontrol (B) (n=4) (5 mg/kg ip) 24 hours before LPS challenge (100 ug/kgiv). Blood samples were harvested at the indicated time point and PAPlevels were determined in plasma using the ELISA (# Asserachrom PAP fromDiagnostica Stago).

FIG. 36 depicts level of active PAI-1 in intraperitoncal fluid (IPF) anduterine horn lysates. Active PAI-1 levels in the intraperitoneal fluid(A) and uterine horn lysates (B). At the 6 hour and Day 7 time pointsactive PAI-1 levels were lower in both intraperitoneal fluid (IPF) andUterine Horn (UH) Lysates in the animals treated with A44V11 antibody incomparison to the isotype control antibody treated animals, nodifference was observed at 72 hour time point. (* p<0.001 calculated bythe Student T-test)

FIG. 37 depicts another example of purification of homogeneityrecombinant 6-His tagged Fab A44.

FIG. 38 depicts purification of homogeneity recombinant 6-His tagged FabA44 complexed with the human wt PAI-1 protein.

FIG. 39(a) depicts the complex crystallization of the Fab A44/PAI-1complex, and FIG. 39 (b) depicts the best optimized crystals.

FIG. 40 depicts the rod-like single crystals of the Fab A44/PAI-1complex.

FIG. 41 depicts Fab A44 recognition the active form of human PAI-1 andthe latent form of cyno PAI-1.

FIG. 42 depicts the PAI-1 epitope recognized by Fab A44 in (A) activehuman PAI-1, and (B) latent cyno PAI-1.

FIG. 43 depicts the heavy chain paratope of the Fab A44/PAI-1 complex.

FIG. 44 depicts the light chain paratope of the Fab A44/PAI-1 complex.

FIG. 45 depicts a sequence alignment of the proposed A44 bindingepitopes of cyno, human, rat, and mouse PAI-1. Sequences are excerptedfrom SEQ ID NO:1 (PAI-1 human), SEQ ID NO: 162 (PAI-1 cyno), SEQ ID NO:163 (PAI-1 mouse), and SEQ ID NO: 164 (PAI-1 rat).

FIG. 46 depicts the comparison of the mouse PAI-1 structure with thestructure of the human PAI-1/A44V11 complex.

FIG. 47 shows the structure of human PAI-1/A44V11 complex and the modelof vibronectin binding to PAI-1.

FIG. 48 depicts peptic peptide coverage of cyno-PAI-1 (SEQ ID NO: 162);95.3% sequence coverage is obtained from 150 overlapping pepticpeptides.

FIG. 49 depicts representative deuterium uptake plots for cyno-PAI-1peptides in the unbound (circle lines), APGv2-bound (x-lines) andA44v11-bound (diamond lines) states. Residue ranges/positions are fromSEQ ID NO:162. (A) most of the peptic peptides showed no differencebetween cyno-PAI-1 alone or bound to either mAb. (B), peptides coveringresidues 44-64 showed similar protection from exchange in both mAb-boundstates. (C), peptides incorporating residues 295-322 incorporate lessdeuterium in both mAb-bound states, however the magnitude of protectionis greater for A44v11.

FIG. 50 depicts hydrogen/deuterium exchange (HDX) comparison ofcyno-PAI-1 alone and bound to A44v11. (A), butterfly plot of the averagerelative fractional exchange with the unbound state above and the boundstate below. The lines correspond to data acquired for the 10 sec, 1min, 5 mm, and 240 min time points. In (B), plot of the difference data(m daltons) from the above plot in (A) for cyno-PAI-1 alone or bound toA44v11.

FIG. 51 depicts HDX comparison of cyno-PAI-1 alone and bound to APGv2.In (A), butterfly plot of the average relative fractional exchange withthe unbound state above and the bound state below. The lines correspondto data acquired for the 10 sec, 1 min, 5 min and 240 min time points.In (B), plot of the difference data from panel (A) above for cyno-PAI-1alone or bound to APGv2.

FIG. 52 depicts HDX comparison of cyno-PAI-1 bound to A44v11 and boundto APGv2. In (A), butterfly plot of the average relative fractionalexchange with the APGv2 bound state above and the A44v 11 bound statebelow. The lines correspond to data acquired for the 10 see, 1 min. 5min and 240 min time points. In (B), plot of the difference data frompanel (A) above for cyno-PAI-1 bound to APGv2 or A44v11.

FIG. 53 depicts the cyno-PAI-1:A44v11 epitope determined by HDX MS. Theresidues of cynoPAI-1 (SEQ ID NO: 162) which show protection fromexchange in the A44v11 antibody-bound state are shown in bold. Theresidues of cyno-PAI-1:A44v11 epitope determined from thecrystallization studies is shown in boxes.

DETAILED DESCRIPTION

The present invention provides antibodies and fragments thereof thatspecifically bind to human PAI-1 and modulate the biological functionsof PA-1. Such antibodies are particularly useful for treatingPAI-1-associated disease or disorders (e.g., fibrosis). The inventionalso provides pharmaceutical comnpositions, as well as nucleic acidsencoding PAI-1 antibodies, recombinant expression vectors and host cellsfor making such antibodies, or fragments thereof. Methods of usingantibodies as disclosed herein to detect PAI-1 or to modulate PAI-1activity, either in vitro or in vivo, are also encompassed by theinvention.

I. Definitions

In order that the present invention may be more readily understood,certain terms are first defined.

As used herein, the term “human PAI-1” refers to a peptide comprising orconsisting of the amino acid sequence listed below:

(SEQ ID NO. 1) VHHPPSYVAHLASDFGVRVFQQVAQASKDRNVVFSPYGVASVLAMLQLTTGGETQQQIQAAMGFKIDDKGMAPALRHLYKELMGPWNKDEISTTDAIFVQRDLKLVQGFMPHFFRLFRSTVKQVDFSEVERARFIINDWVKTHTKGMISNLLGKGAVDQLTRLVLVNALYFNGQWKTPFPDSSTHRRLFHKSDGSTVSVPMMAQTNKFNYTEFTTPDGHYYDILELPYHGDTLSMFIAAPYEKEVPLSALTNILSAQLISHWKGNMTRLPRLLVLPKFSLETEVDLRKPLENLGMTDMFRQFQADFTSLSDQEPLHVAQALQKVKIEVNESGTVASSSTAVIVSARMAPEEIIMDRPFLFVVRHNPTGTVLFMGQVMEP, or a fragment thereof.

As used herein, the term “antibody” refers to immunoglobulin moleculescomprising four polypeptide chains, two heavy (H) chains and two light(L) chains inter-connected by disulfide bonds, as well as multimersthereof (e.g., IgM). Each heavy chain comprises a heavy chain variableregion (abbreviated V_(H) or VH) and a heavy chain constant region(C_(H) or CH). The heavy chain constant region comprises three domains.C_(H)1. C_(H)2 and C_(H)3. Each light chain comprises a light chainvariable region (abbreviated V_(H) or VL) and a light chain constantregion (C_(L) or CL). The light chain constant region comprises onedomain (C_(L)1). The V_(H) and V_(L) regions can be further subdividedinto regions of hypervariability, termed complementarity determiningregions (CDRs), interspersed with regions that are more conserved,termed framework regions (FR). Each V_(H) and V_(L) is composed of threeCDRs and four FRs, arranged from amino-terminus to carboxy-terminus inthe following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4.

As used herein, the term “antigen-binding fragment” of an antibodyincludes any naturally occurring, enzymatically obtainable, synthetic,or genetically engineered polypeptide or glycoprotein that specificallybinds an antigen to form a complex. Antigen-binding fragments of anantibody may be derived, e.g., from full antibody molecules using anysuitable standard techniques such as proteolytic digestion orrecombinant genetic engineering techniques involving the manipulationand expression of DNA encoding antibody variable and optionally constantdomains. Non-limiting examples of antigen-binding portions include: (i)Fab fragments; (ii) F(ab′)₂ fragments; (iii) Fd fragments; (iv) Fvfragments; (v) single-chain Fv (scFv) molecules; (vi) dAb fragments; and(vii) minimal recognition units consisting of the amino acid residuesthat mimic the hypervariable region of an antibody (e.g., an isolatedcomplementarity determining region (CDR)). Other engineered molecules,such as diabodies, triabodies, tetrabodies and minibodies, are alsoencompassed within the expression “antigen-binding fragment.”

As used herein, the term “CDR” or “complementarity determining region”means the noncontiguous antigen combining sites found within thevariable region of both heavy and light chain polypeptides. Theseparticular regions have been described by Kabat et al., J. Biol. Chem.252, 6609-6616 (1977) and Kabat et al., Sequences of protein ofimmunological interest (1991), and by Chothia et al., J. Mol. Biol.196:901-917 (1987) and by MacCallum et al., J. Mol. Biol. 262:732-745(1996) where the definitions include overlapping or subsets of aminoacid residues when compared against each other. The Kabat definition isbased on sequence variability. The IMGT unique numbering for all IG andTR V-regions of all species relies on the high conservation of thestructure of the variable region (Lefranc, Mp et al., Dev comp. Immunol.27:55-77, 2003). IMGT numbering, set up after aligning more than 5,000sequences takes into account and combines the definition of theframework and CDRs. The Clothia definition is based on the location ofthe structural loop regions. The Contact definition (MacCallum et al.)is based on an analysis of the complex crystal structures andantibody-antigen interactions. The amino acid residues which encompassthe CDRs as defined by each of the above cited references are set forthfor comparison. In one embodiment disclosed herein, the term “CDR” is aCDR as defined by the Kabat definition. In another embodiment disclosedherein, the CDR is a CDR as defined by IMGT.

As used herein the term “framework (FR) amino acid residues” refers tothose amino acids in the framework region of an Ig chain. The term“framework region” or “FR region” as used herein, includes the aminoacid residues that are part of the variable region, but are not part ofthe CDRs (e.g., using the Contact definition of CDRs). Therefore, avariable region framework is between about 100-120 amino acids in lengthbut includes only those amino acids outside of the CDRs.

The present invention also encompasses “conservative amino acidsubstitutions” in the CDR amino acid sequences of the antibodiesdisclosed herein, i.e., amino acid sequence modifications which do notabrogate the binding of the antibody to the antigen, i.e., PAI-1. Aconservative substitution is a substitution of a native amino acidresidue with a nonnative residue such that there is little or no effecton the polarity or charge of the amino acid residue at that position.For example, a conservative substitution results from the replacement ofa non-polar residue in a polypeptide with any other non-polar residue.Furthermore, any native residue in the polypeptide may also besubstituted with alanine, as has been previously described for “alaninescanning mutagenesis” (Cunningham et al., Science 244:1081-85 (1989)).Conservative amino acid substitutions include the substitution of anamino acid in one class by an amino acid of the same class, where aclass is defined by common physicochemical amino acid side chainproperties and high substitution frequencies in homologous proteinsfound in nature, as determined, for example, by a standard Dayhofffrequency exchange matrix or BLOSUM matrix. Six general classes of aminoacid side chains have been categorized and include: Class I (Cys); ClassII (Ser, Thr, Pro, Ala, Gly); Class III (Asn, Asp, Gln, Glu); Class IV(His, Arg, Lys); Class V (Ile, Leu, Val, Met); and Class VI (Phe, Tyr,Trp). For example, substitution of an Asp for another class III residuesuch as Asn, Gln, or Glu, is a conservative substitution. Thus, apredicted nonessential amino acid residue in a PAI-1 antibody isreplaced with another amino acid residue from the same class. Methods ofidentifying amino acid conservative substitutions which do not eliminateantigen binding are well-known in the art (see. e.g., Brummell et al.,Biochem. 32:1180, 1993; Kobayashi et al. Protein Eng. 12:879, 1999; andBurks et al. Proc. Natl. Acad. Sci. USA 94:412, 1997). General rules forconservative amino acid substitutions are set forth in Table 1 below.

TABLE 1 Conservative Amino Acid Substitutions Original Exemplary SelectResidues Substitutions Substitutions Ala Val, Leu, Ile Val Arg Lys, Gln,Asn Lys Asn Gln, His, Lys, Arg Gln Asp Glu Glu Cys Ser Ser Gln Asn AsnGlu Asp Asp Gly Pro, Ala Ala His Asn, Gln, Lys, Arg Arg Ile Leu, Val,Met, Ala, Leu Phe, Norleucine Leu Norleucine, Ile, Ile Val, Met, Ala,Phe Lys Arg, Gln, Asn Arg Met Leu, Phe, Ile Leu Phe Leu, Val, Ile, Ala,Leu Tyr Pro Ala Ala Ser Thr Thr Thr Ser Ser Trp Tyr, Phe Tyr Tyr Trp,Phe, Thr, Ser Phe Val Ile, Met, Leu, Phe, Leu Ala, Norleucine

Conservative amino acid substitutions also encompass non-naturallyoccurring amino acid residues that are typically incorporated bychemical peptide synthesis rather than by synthesis in biologicalsystems. These include peptidomimetics, and other reversed or invertedforms of amino acid moieties.

Conservative modifications to the amino acid sequence (and thecorresponding modifications to the encoding nucleotides) are expected toproduce PAI-1 antibodies having functional and chemical characteristicssimilar to those of naturally occurring PAI-1 antibodies. In contrast,substantial modifications in the functional or chemical characteristicsof PAI-1 antibodies may be accomplished by selecting substitutions thatdiffer significantly in their effect on maintaining (a) the structure ofthe molecular backbone in the area of the substitution, for example, asa sheet or helical conformation, (b) the charge or hydrophobicity of themolecule at the target site, or (c) the bulk of the side chain.Naturally occurring residues may be divided into groups based on commonside chain properties:

1) hydrophobic: norleucine, Met, Ala, Val, Lcu, Ile;

2) neutral hydrophilic: Cys, Ser, Thr;

3) acidic: Asp, Glu;

4) basic: Asn, Gln, His, Lys, Arg;

5) residues that influence chain orientation: Gly, Pro; and

6) aromatic: Trp, Tyr, Phe.

Non-conservative substitutions may involve the exchange of a member ofone of these classes for a member from another class. Such substitutedresidues may be introduced into regions of the human PAI-1 antibody thatare homologous with non-human PAI-1 antibody, or into the non-homologousregions of the molecule.

In certain aspects, the heavy or light chain variable regions may be99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% identical to any ofthe variable region sequences disclosed herein.

As used herein, the term “specifically binds to” refers to the abilityof an antibody or an antigen-binding fragment thereof to bind to anantigen with an Kd that is lower than 1×10⁻⁶ M, 1×10⁻⁷ M, 1×10⁻⁸ M,1×10⁻⁹ M, 1×10⁻¹⁰ M, 1×10⁻¹¹ M, 1×10⁻¹² M, or less. The term alsoencompasses refers to the ability of an antibody or an antigen-bindingfragment thereof to bind to an antigen with an affinity that is at leasttwo-fold greater than its affinity for a nonspecific antigen.

The disclosure also provides antibodies that competitively inhibitbinding of an antibody to an epitope disclosed herein as determined byany method known in the art for determining competitive binding, forexample, the immunoassays described herein. In certain embodiments, theantibody competitively inhibits binding to the epitope by at least 95%,at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, atleast 60%, or at least 50%.

As used herein, the term “antigen” refers to the binding site or epitoperecognized by an antibody or antigen binding fragment thereof.

As used herein, the term “vector” is intended to refer to a nucleic acidmolecule capable of transporting another nucleic acid to which it hasbeen linked. One type of vector is a “plasmid,” which refers to acircular double stranded DNA loop into which additional DNA segments maybe ligated. Another type of vector is a viral vector, wherein additionalDNA segments may be ligated into the viral genome. Certain vectors arecapable of autonomous replication in a host cell into which they areintroduced (e.g., bacterial vectors having a bacterial origin ofreplication and episomal mammalian vectors). Other vectors (e.g.,non-episomal mammalian vectors) can be integrated into the genome of ahost cell upon introduction into the host cell, and thereby arereplicated along with the host genome. Moreover, certain vectors arecapable of directing the expression of genes to which they areoperatively linked. Such vectors are referred to herein as “recombinantexpression vectors” (or simply, “expression vectors”). In general,expression vectors of utility in recombinant DNA techniques are often inthe form of plasmids. The terms, “plasmid” and “vector” may be usedinterchangeably. However, the Invention is intended to include suchother forms of expression vectors, such as viral vectors (e.g.,replication defective retroviruses, adenoviruses and adeno-associatedviruses), which serve equivalent functions.

Numerous expression vector systems may be employed for the purposes ofthis invention. For example, one class of vector utilizes DNA elementswhich are derived from animal viruses such as bovine papilloma virus,polyoma virus, adenovirus, vaccinia virus, baculovirus, retroviruses(RSV, MMTV or MOMLV) or SV40 virus. Others involve the use ofpolycistronic systems with internal ribosome binding sites.Additionally, cells which have integrated the DNA into their chromosomesmay be selected by introducing one or more markers which allow selectionof transfected host cells. The marker may provide for prototrophy to anauxotrophic host, biocide resistance (e.g., antibiotics) or resistanceto heavy metals such as copper. The selectable marker gene can either bedirectly linked to the DNA sequences to be expressed, or introduced intothe same cell by cotransformation. Additional elements may also beneeded for optimal synthesis of mRNA. These elements may include signalsequences, splice signals, as well as transcriptional promoters,enhancers, and termination signals. In particular embodiments the clonedvariable region genes are inserted into an expression vector along withthe heavy and light chain constant region genes (e.g. human) syntheticas discussed above.

More generally, once a vector or DNA sequence encoding an antibody, orfragment thereof, has been prepared, the expression vector may beintroduced into an appropriate host cell. That is, the host cells may betransformed. Introduction of the plasmid into the host cell can beaccomplished by various techniques well known to those of skill in theart. These include, but are not limited to, transfection (includingelectrophoresis and electroporation), protoplast fusion, calciumphosphate precipitation, cell fusion with enveloped DNA, microinjection,and infection with intact virus. See, Ridgway, A. A. G. “MammalianExpression Vectors” Chapter 24.2, pp. 470-472 Vectors. Rodriguez andDenhardt, Eds. (Butterworths, Boston. Mass. 1988). An embodimentdisclosed herein is plasmid introduction into the host viaelectroporation. The transformed cells are grown under conditionsappropriate to the production of the light chains and heavy chains, andassayed for heavy or light chain protein synthesis. Exemplary assaytechniques include enzyme-linked immunosorbent assay (ELISA),radioimmunoassay (RIA), or fluorescence-activated cell sorter analysis(FACS), immunohistochemistry and the like.

As used herein, the term “transformation” shall be used in a broad senseto refer to the introduction of DNA into a recipient host cell thatchanges the genotype and consequently results in a change in therecipient cell.

“Host cells” refers to cells that have been transformed with vectorsconstructed using recombinant DNA techniques and encoding at least oneheterologous gene. In descriptions of processes for isolation ofpolypeptides from recombinant hosts, the terms “cell” and “cell culture”are used interchangeably to denote the source of antibody unless it isclearly specified otherwise. In other words, recovery of polypeptidefrom the “cells” may mean either from spun down whole cells, or from thecell culture containing both the medium and the suspended cells.

It should be understood that this term is intended to refer not only tothe particular subject cell but to the progeny of such a cell. Becausecertain modifications may occur in succeeding generations due to eithermutation or environmental influences, such progeny may not, in fact, beidentical to the parent cell, but are still included within the scope ofthe term “host cell” as used herein.

As used herein, the term “treat,” “treating,” and “treatment” refer totherapeutic or preventative measures described herein. The methods of“treatment” employ administration to a subject, an antibody or antigenbinding fragment disclosed herein, for example, a subject having aPAI-1-associated disease or disorder (e.g., a fibrotic disease) orpredisposed to having such a disease or disorder, in order to prevent,cure, delay, reduce the severity of, or ameliorate one or more symptomsof the disease or disorder or recurring disease or disorder, or in orderto prolong the survival of a subject beyond that expected in the absenceof such treatment.

As used herein, the term “PAI-1-associated disease or disorder” includesdisease states with or without symptoms associated with a disease state,where altered levels or activity of PAI-1 are found. ExemplaryPAI-1-associated diseases or disorders include various types offibrosis.

As used herein, the term “effective amount” refers to that amount of anantibody or an antigen binding fragment thereof that binds PAI-1, whichis sufficient to effect treatment, prognosis or diagnosis of aPAI-1-associated disease or disorder, as described herein, whenadministered to a subject. A therapeutically effective amount will varydepending upon the subject and disease condition being treated, theweight and age of the subject, the severity of the disease condition,the manner of administration and the like, which can readily bedetermined by one of ordinary skill in the art. The dosages foradministration can range from, for example, about 1 ng to about 10,000mg, about 1 ug to about 5,000 mg, about 1 mg to about 1,000 mg, about 10mg to about 100 mg, of an antibody or antigen binding fragment thereof,disclosed herein. Dosage regiments may be adjusted to provide theoptimum therapeutic response. An effective amount is also one in whichany toxic or detrimental effects (i.e., side effects) of an antibody orantigen binding fragment thereof are minimized or outweighed by thebeneficial effects.

As used herein, the term “subject” or “mammal” includes any human ornon-human animal.

As used herein, the term “epitope” refers to an antigenic determinantthat interacts with a specific antigen binding site in the variableregion of an antibody molecule known as a paratope. A single antigen mayhave more than one epitope. Thus, different antibodies may bind todifferent areas on an antigen and may have different biological effects.Epitopes may be either conformational or linear. A conformationalepitope is produced by spatially juxtaposed amino acids from differentsegments of the linear polypeptide chain. A linear epitope is oneproduced by adjacent amino acid residues in a polypeptide chain.

It is noted here that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referenceunless the context clearly dictates otherwise.

II. Anti-PAI-1 Antibodies

In one aspect the invention provides antibodies, or antigen bindingfragments thereof, that specifically bind to human PAI-1. Exemplary VH,VL and CDR amino acid sequences and nucleotide sequences of theantibodies disclosed herein are set forth in Table 2. CDR regions shownin Table 2 are defined by IMGT.

TABLE 2 VH, VL and CDR amino acid sequences of exemplary anti-PAI-1antibodies or fragments therof SEQ ID ANTIBODY SEQUENCE NO mA105 VHQVQLQQSGAELMKPGASVKISCKATGFTFSIYWIEWVKQ  2RPGLGLEWIGEILPGSGSTNYNEKFKGKATFTADTSSNTAFMQLSSLTSEDSAVYYCARGGLYYDLDYWGQGTILTVS SAKTTPP mA105 VLDVVMTQTPLTLSVTTGQPASTSCKSSQSLLDSDGKTYLN  3WLLQRPGQSPQRLISLVSKLDSGVPDRFTGSGSGTDFTLKLSRVEGADLGVYYCWQDRHFPRTFGGGTKLEIKRAD mA39 VHQVQLQQSGAELMKPGASVKISCKATGYTFNIYWIQWVK  4QRPGHGLEWIGEILPGSNTNYNEKFKDKATFTADSSSNTAYMQLSSLTSEDSAVYYCARLGIGLRGALDYWGQGTSV TVSSAKTTPP mA39 VLDIQMTHSPASLSASVGETVTITCRASENIYSYLAWYHQK  5QGKSPQLLVYNAKTLAEGVPSRFSGSGSGTQFSLNIKSL QPEDFGTFYCQHRYGSWTFGGGTKLEIKRADmA44 VH EMQLQESGPSLVKPSQTLSLTCSVTGDSMTNGYWNWIR  6KFPGNKLEYMGYITYSGSTYYNPSLKGRISITRNTSKNQYYLQLSSVTTEDTATYYCARWHYGSPYYFDYWGQGTTLT VSSAKTTPP mA44 VLDIKMTQSPSSMYASLGERVTITCKASQDINSYLSWLQQK  7PGKSPKTLIYRANRSVDGVPSRFSGSGSGQDYSLTISSLE YEDMGIYYCLQYDEFPPTFGGGTKLEIKRADmA71 VH QVQLQQSGAELMKPGASVKISCKATGFTFSTYWIEWIKQ  8RPGHGLDWIGEILPGSGNTNYNEKFKGKATFTADTSSNTVYMQLSSLTSEDSAVYYCARGGLYYNLDSWGQGTTLT VSSAKTTPP mA71 VLDVVMTQTPLTLSVTIGQPASISCKSSQSLLDSDGKTYLY  9WLLQRPGQSPKRLIYLVSKLDSGVPDRFTGSGSGTDFTLKISRVEAEDLGVYYCWQDTHFPRTFGGGTKLEIKRAD mA75 VHQGQLQQSGAELMKPGASVKISCKASGFTFSTYWIAWLK 80QRPGHGLEWIAEILPGSGLTNYNEIFRGKATFTADTSSNTAYMQLSSLTSEDSAVYYCARGGLYYAMDYWGQGTSVT VSSAKTTAP mA75 VLDVVMTQTPLTLSVTIGQPASICKSSQSLLDSEGKTYLNW 81LFQRPGQSPKRLIYLVCKLDCGVPDRFTGSGSGTDFTLKISRVEGEDLGVYYCWQGSHFPQTFGGGTKLEIKRAD mB109 VHEVQLQQSGSVLARPGTSVKMSCKASGYSFTSYWMHWV 10KQRPGQGLEWMGAIYPGNSGQGLDWIGAIYPGNSDTTYNQKFEDKAKLTAVASASTAYMEVSSLTNEDSAVYYCTR GLRRWGAMDYWGQGTSVTVSSAKTTPPmB109 VL DIVMTQSHKFMSTSAGDRVSIPCKASQDVSSAVAWYQQ 11KLGQSPKLLIYSASFRYTGVPDRFTGSGSGTDFTFTISSVQAEDLAVYYCQQHYSSPYTFGGGTNLEIKRAD mB28 VHQVQLQQSGAELMKPGASVKISCKATGYTFSISWIEWIKQ 12RPGGLEWIGKILPGSGGANYNEKFKGKATVTADTSSNTVYMQLSSLTSEDSAVYYCARLSTGTRGAFDYWGQGTTLT VSSAKTTPP mB28 VLDIQLTQSPASLSASVGATVTITCRASENVYSYLAWYQQK 13QGKSPQLLVYNAKTLAEGVPSRFSGSGSGTQFSLKINYL QPEDFGSYYCQHHYGTPPTFGGGTKVEIKRADmC45 VH QVQLQQSGVELVRPGTSVKVSCKASGYAFTNYLIEWIKQ 14RPGQGLEWIGVTHPGSGVTNYNEKFKGKAILTADKSSSTAYMQLSSLTSDDSAVYFCARDYYGSSHGLMDYWGQGT SVTVSS mC45 VLDIKMTQSPSSMYASLGERVTITCKASQDINSYLSWFQQK 15PGKSPKTLIYRANRLVDGVPSRFSGSGSGQDYSLTISSLE YEDMGIYYCLQYDEFPRTFGGGTKLEIKmE16 VH EVKLVESGGGLVKPGGSLKLSCAASGFTFSNYGMSWVR 16QTPEKGLGWVASLRTGGNTYYSDSVKGRFTTSRDNDRNILYLQMSSLTSEDTAVYYCARGLRHWGYFDVWGAGTTVTVSS mE16 VLDIVMTQSHKFMSTSVGDRVNITCKASQDVSTAVGWYQQ 17EPGQSPKLLIYSASNRHTGVPDRFTGSGSGTDFTFTISSVQ AEDLAVYYCQQHYSSPWTFGGGTKLEIKmE21 VH EVQLQQSGAELVRSGASVKLSCTASGFNIKDYYMHWVK 18QRPEQGLEWIGWIDPENGDTEYDPKFQAKATMTADTSSNTAYLQLSSLTSEDTAVYYCMYGNYPYFDYWGQGTTLTVSS mE21 VLDIQMTQTTSSLSASLGDRVTISCRASQDISNYLNWYQQK 19PDGTVKLLIYYTSRLHSGVPSRFSGSGSGTDYSLTISNLE QEDIATYFCQQGNTLPWTFGGGTKLEIKmA105 ARGGLYYDLDY 20 HCDR3 mA105 ILPGSGST 21 HCDR2 mA105 GFTFSIYW 22HCDR1 mA105 WQDRHFPRT 23 LCD3 mA105 LVS 24 mA71 LCDR2 mA105 QSLLDSDGKTY25 mA71 LCDR1 mA39 ARLGIGLRGALDY 26 HCDR3 mA39 ILPGSNT 27 HCDR2 mA39GYTFNIYW 28 HCDR1 mA39 QHRYGSPWT 29 LCDR3 mA39 NAK 30 LCDR2 mA39 ENIYSY31 LCDR1 mA44 ARWHYGSPYYFDY 32 HCDR3 mA44 ITYSGST 33 HCDR2 mA44 GDSMTNGY34 HCDR1 mA44 LQYDEFPPT 35 LCDR3 mA44 RAN 36 LCDR2 mA44 QDINSY 37 LCDR1mA71 ARGGLYYNLDS 38 HCDR3 mA71 ILPGSGNT 39 HCDR2 mA71 GFTFSTYW 40 HCDR1mA71 WQDTHFPRT 41 LCDR3 mA71 LVS 42 LCDR2 mA71 QSLLDSDGKTY 43 LCDR1 mA75ARGGLYYAMDY 44 HCDR3 mA75 ILPGSGLT 45 HCDR2 mA75 GFTFSTYW 46 HCDR1 mA75WQGSHFPQT 47 LCDR3 mA75 LVC 48 LCDR2 mA75 QSLLDSEGKTY 49 LCDR1 mB109TRGLRRWGAMDY 50 HCDR3 mB109 ILPGSGLT 51 HCDR2 mB109 GFTFSTYW 52 HCDR1mB109 QQHYSSPYT 53 LCDR3 mB109 SAS 54 LCDR2 mB109 QDVSSA 55 LCDR1 mB28ARLSTGTRGAFDY 56 HCDR3 mB28 ITPGSGGA 57 HCDR2 mB28 GYTFSISW 58 HCDR1mB28 QHHYGTPPT 59 LCDR3 mB28 NAK 60 LCDR2 mB28 ENVYSY 61 LCDR1 mC45ARDYYGSSHGLMDY 62 HCDR3 mC45 IHPGSGVT 63 HCDR2 mC45 GYAFTNYL 64 HCDR1mC45 LQYDEFPRT 65 LCDR3 mC45 RAN 66 LCDR2 mC45 QDINSY 67 LCDR1 mE16ARGLRHWGYFDV 68 HCDR3 mE16 LRTGGNT 69 HCDR2 mE16 GFTFSNYG 70 HCDR1 mE16QQHYSSPWT 71 LCDR3 mE16 SAS 72 LCDR2 mE16 QDISNY 73 LCDR1 mE21MYGNYPYYFDY 74 HCDR3 mE21 IDPENGDT 75 HCDR2 mE21 GFNIKDYY 76 HCDR1 mE21QQGNTLPWT 77 LCDR3 mE21 YTS 78 LCDR2 mE21 QDISNY 79 LCDR1 m murine; VH =variable heavy chain; VL = variable light chain;

In another embodiment, the present invention provides anti-PAI-1antibodies that bind to the same epitope or competitively inhibit anantibody, or antigen binding fragment thereof comprising the VH and VLregion amino acid sequences set forth in SEQ ID NO: 6 and 7respectively. Such antibodies can be identified using routinecompetition binding assays including, for example, surface plasmonresonance (SPR)-based competition assays.

III. Modified Anti-PAI-1 Antibodies

In certain embodiments, anti-PAI-1 antibodies disclosed herein maycomprise one or more modifications. Modified forms of anti-PAI-1antibodies disclosed herein can be made using any techniques known inthe art.

I) Reducing Immunogenicity

In certain embodiments, anti-PAI-1 antibodies, or antigen bindingfragments thereof, disclosed herein are modified to reduce theirimmunogenicity using art-recognized techniques. For example, antibodies,or fragments thereof, can be chimerized, humanized, or deimmunized.

In one embodiment, an antibody, or antigen binding fragments thereof,disclosed herein may be chimeric. A chimeric antibody is an antibody inwhich different portions of the antibody are derived from differentanimal species, such as antibodies having a variable region derived froma murine monoclonal antibody and a human immunoglobulin constant region.Methods for producing chimeric antibodies, or fragments thereof, areknown in the art. See e.g., Morrison, Science 229:1202, 1985; Oi et al.,BioTechniques 4:214, 1986; Gillies et al., J. Immunol. Methods 125:191,1989; U.S. Pat. Nos. 5,807,715; 4,816,567; and 4,816,397, which areincorporated herein by reference in their entireties. Techniquesdeveloped for the production of “chimeric antibodies” (Morrison et al.,Proc. Natl. Acad. Sci. 81:851, 1984; Neuberger et al., Nature 312:604,1984: Takeda et al., Nature 314:452, 1985) may be employed for thesynthesis of said molecules. For example, a genetic sequence encoding abinding specificity of a mouse anti-PAI-1 antibody molecule may be fusedtogether with a sequence from a human antibody molecule of appropriatebiological activity. As used herein, a chimeric antibody is a moleculein which different portions are derived from different animal species,such as those having a variable region derived from a murine monoclonalantibody and a human immunoglobulin constant region, e.g., humanizedantibodies.

In another embodiment, an antibody, or antigen binding fragment thereof,as disclosed herein is humanized. Humanized antibodies have a bindingspecificity comprising one or more complementarity determining regions(CDRs) from a non-human antibody and framework regions from a humanantibody molecule. Often, framework residues in the human frameworkregions will be substituted with the corresponding residue from the CDRdonor antibody to alter, or improve, antigen binding. These frameworksubstitutions are identified by methods well known in the art, e.g., bymodeling of the interactions of the CDR and framework residues toidentify framework residues important for antigen binding and sequencecomparison to identify unusual framework residues at particularpositions. See e.g. Queen et al., U.S. Pat. No. 5,585,089; Riechmann etal., Nature 332:323, 1988, which are incorporated herein by reference intheir entireties. Antibodies can be humanized using a variety oftechniques known in the art including, for example, CDR-grafting (EP239,400; International Publication No. WO 91/09967; U.S. Pat. Nos.5,225,539; 5,530,101; and 5,585,089), veneering or resurfacing (EP592,106; EP 519,596; Padlan, Molecular Immunology 28:489, 1991;Studnicka et al., Protein Engineering 7:805, 1994; Roguska, et al., PNAS91:969, 1994), and chain shuffling (U.S. Pat. No. 5,565,332).

In a particular embodiment, a humanization method is employed that isbased on the impact of the molecular flexibility of the antibody duringand at immune recognition (see International Publication No.WO2009/032661, which is incorporated herein by reference in Itsentirety). Protein flexibility is related to the molecular motion of theprotein molecule. Protein flexibility is the ability of a whole protein,a part of a protein or a single amino acid residue to adopt an ensembleof conformations which differ significantly from each other. Informationabout protein flexibility can be obtained by performing protein X-raycrystallography experiments (see, for example. Kundu et al., Biophys. J.83:723, 2002), nuclear magnetic resonance experiments (see, for example,Freedberg et al., J. Am. Chem. Soc. 120:7916, 1998) or by runningmolecular dynamics (MD) simulations. An MD simulation of a protein isdone on a computer and allows one to determine the motion of all proteinatoms over a period of time by calculating the physical interactions ofthe atoms with each other. The output of a MD simulation is thetrajectory of the studied protein over the period of time of thesimulation. The trajectory is an ensemble of protein conformations, alsocalled snapshots, which are periodically sampled over the period of thesimulation, e.g. every 1 picosecond (ps). It is by analyzing theensemble of snapshots that one can quantify the flexibility of theprotein amino acid residues. Thus, a flexible residue is one whichadopts an ensemble of different conformations in the context of thepolypeptide within which that residue resides. MD methods are known inthe art, see, e.g., Brooks et al. “Proteins: A Theoretical Perspectiveof Dynamics. Structure and Thermodynamics” (Wiley, New York, 1988).Several software enable MD simulations, such as Amber (see Case et al.J. Comp. Chem. 26:1668, 2005; Brooks et al. J. Comp. Chem. 4:187, 1983;and MacKerell et al. (1998) in “The Encyclopedia of ComputationalChemistry” vol. 1:271-177, Schleyer et al., eds. Chichester: John Wiley& Sons) or Impact (see Rizzo et al. J. Am. Chem. Soc.; 122:12898, 2000).

Most protein complexes share a relatively large and planar buriedsurface and it has been shown that flexibility of binding partnersprovides the origin for their plasticity, enabling them toconformationally adapt to each other (Sundberg and Mariuzza, Structure8, R137-R142, 2000). As such, examples of “induced lit” have been shownto play a dominant role in protem-protein interfaces. In addition, thereis a steadily increasing body of data showing that proteins actuallybind ligands of diverse shapes, sizes and composition (Protein Science11:184-187, 2002) and that the conformational diversity appears to be anessential component of the ability to recognize different partners(James et al., Science 299:1362, 2003). Flexible residues are involvedin the binding of protein-protein partners (Grunberg et al., Structure14, 683, 2006).

The flexible residues can adopt a variety of conformations that providean ensemble of interaction areas that are likely to be recognized bymemory B cells and to trigger an immunogenic response. Thus, an antibodycan be humanized by modifying a number of residues from the framework sothat the ensemble of conformations and of recognition areas displayed bythe modified antibody resemble as much as possible those adopted by ahuman antibody. That can be achieved by modifying a limited number ofresidues by: (1) building a homology model of the parent mAb and runningan MD simulation; (2) analyzing the flexible residues and identificationof the most flexible residues of a non-human antibody molecule, as wellas identifying residues or motifs likely to be a source of heterogeneityor of degradation reaction; (3) identifying a human antibody whichdisplays the most similar ensemble of recognition areas as the parentantibody: (4) determining the flexible residues to be mutated, residuesor motifs likely to be a source of heterogeneity and degradation arealso mutated; and (5) checking for the presence of known T cell or Bcell epitopes. The flexible residues can be found using an MDcalculation as taught herein using an implicit solvent model, whichaccounts for the interaction of the water solvent with the protein atomsover the period of time of the simulation.

Once the set of flexible residues has been identified within thevariable light and heavy chains, a set of human heavy and light chainvariable region frameworks that closely resemble that of the antibody ofinterest is identified. That can be done, for example, using a BLASTsearch on the set of flexible residues against a database of antibodyhuman germ line sequence. It can also be done by comparing the dynamicsof the parent mAb with the dynamics of a library of germ line canonicalstructures. The CDR residues and neighboring residues are excluded fromthe search to ensure high affinity for the antigen is preserved.Flexible residues then are replaced.

When several human residues show similar homologies, the selection isdriven also by the nature of the residues that are likely to affect thesolution behavior of the humanized antibody. For instance, polarresidues will often occur in exposed flexible loops over hydrophobicresidues. Residues which are a potential source of instability andheterogeneity are also mutated even if there are found in the CDRs. Thatwill include exposed methionines as sulfoxide formation can result fromoxygen radicals, proteolytic cleavage of acid labile bonds such as thoseof the Asp-Pro dipeptide (Drug Dev. Res. 61:137, 2004), deamidationsites found with an exposed asparagine residue followed by a small aminoacid, such as Gly, Ser, Ala, H is, Asn or Cys (J. Chromatog. 837:35,2006) and N-glycosylation sites, such as the Asn-X-Ser/Thr site.Typically, exposed methionines will be substituted by a Leu, exposedasparagines will be replaced by a glutamine or by an aspartate, or thesubsequent residue will be changed. For the glycosylation site(Asn-X-Ser/Thr), either the Asn or the Ser/Thr residue will be changed.

The resulting composite antibody sequence is checked for the presence ofknown B cell or linear T-cell epitopes. A search is performed, forexample, with the publicly available Immune Epitope Data Base (IEDB)(PLOS Biol. (2005) 3(3)e91). If a known epitope is found within thecomposite sequence, another set of human sequences is retrieved andsubstituted. Thus, unlike the resurfacing method of U.S. Pat. No.5,639,641, both B-cell-mediated and T-cell-mediated immunogenicresponses are addressed by the method. The method also avoids the issueof loss of activity that is sometimes observed with CDR grafting (U.S.Pat. No. 5,530,101). In addition, stability and solubility issues alsoare considered in the engineering and selection process, resulting in anantibody that is optimized for low immunogenicity, high antigen affinityand improved biophysical properties.

In some embodiments, de-immunization can be used to decrease theimmunogenicity of and antibody, or antigen binding fragment thereof. Asused herein, the term “dc-immunization” includes alteration of anantibody, or antigen binding fragment thereof to modify T cell epitopes(see, e.g., International Publication Nos. WO9852976A1, WO0034317A2).For example, VH and VL, sequences from the starting antibody may beanalyzed and a human T cell epitope “map” may be generated from each Vregion showing the location of epitopes in relation tocomplementarity-determining regions (CDRs) and other key residues withinthe sequence. Individual T cell epitopes from the T cell epitope map areanalyzed in order to identify alternative amino acid substitutions witha low risk of altering activity of the final antibody. A range ofalternative VH and VL sequences are designed comprising combinations ofamino acid substitutions and these sequences are subsequentlyincorporated into a range of PAI-1-specific antibodies or fragmentsthereof for use in the diagnostic and treatment methods disclosedherein, which are then tested for function. Typically, between 12 and 24variant antibodies are generated and tested. Complete heavy and lightchain genes comprising modified V and human C regions are then clonedinto expression vectors and the subsequent plasmids introduced into celllines for the production of whole antibody. The antibodies are thencompared in appropriate biochemical and biological assays, and theoptimal variant is identified.

ii) Effector Functions and Fc Modifications

Anti-PAI-1 antibodies disclosed herein may comprise an antibody constantregion (e.g. an IgG constant region, a human IgG constant region, ahuman IgG1 or IgG4 constant region) which mediates one or more effectorfunctions. For example, binding of the C1 component of complement to anantibody constant region may activate the complement system. Activationof complement is important in the opsonization and lysis of cellpathogens. The activation of complement also stimulates the inflammatoryresponse and may also be involved in autoimmune hypersensitivity.Further, antibodies bind to receptors on various cells via the Fcregion, with a Fc receptor binding site on the antibody Fc regionbinding to a Fc receptor (FcR) on a cell. There are a number of Fcreceptors which are specific for different classes of antibody,including IgG (gamma receptors), IgE (epsilon receptors), IgA (alphareceptors) and IgM (mu receptors). Binding of antibody to Fc receptorson cell surfaces triggers a number of important and diverse biologicalresponses including engulfment and destruction of antibody-coatedparticles, clearance of immune complexes, lysis of antibody-coatedtarget cells by killer cells (called antibody-dependent cell-mediatedcytotoxicity, or ADCC), release of inflammatory mediators, placentaltransfer and control of immunoglobulin production. In certainembodiments, the antibodies, or fragments thereof disclosed herein bindto an Fc-gamma receptor. In alternative embodiments, anti-PAI-1antibodies disclosed herein may comprise a constant region which isdevoid of one or more effector functions (e.g., ADCC activity) or isunable to bind Fc receptor.

Certain embodiments disclosed herein include anti-PAI-1 antibodies inwhich at least one amino acid in one or more of the constant regiondomains has been deleted or otherwise altered so as to provide desiredbiochemical characteristics such as reduced or enhanced effectorfunctions, the ability to non-covalently dimerize, increased ability tolocalize at a particular site in the body (e.g., the site of a tumor orto a particular organ), reduced serum half-life, or increased serumhalf-life when compared with a whole, unaltered antibody ofapproximately the same immunogenicity. For example, certain antibodies,or fragments thereof, for use in the diagnostic and treatment methodsdescribed herein are domain deleted antibodies which comprise apolypeptide chain similar to an immunoglobulin heavy chain, but whichlack at least a portion of one or more heavy chain domains. Forinstance, in certain antibodies, one entire domain of the constantregion of the modified antibody will be deleted, for example, all orpart of the CH2 domain will be deleted.

In certain other embodiments, anti-PAI-1 antibodies comprise constant,regions derived from different antibody isotypes (e.g., constant regionsfrom two or more of a human IgG1, IgG2, IgG3, or IgG4). In otherembodiments, anti-PAI-1 antibodies comprises a chimeric hinge (i.e., ahinge comprising hinge portions derived from hinge domains of differentantibody isotypes, e.g., an upper hinge domain from an IgG4 molecule andan IgG1 middle hinge domain). In one embodiment, an anti-PAI-1 antibodycomprises an Fc region or portion thereof from a human IgG4 molecule anda Ser228Pro mutation (Kabat numbering) in the core hinge region of themolecule.

In certain anti-PAI-1 antibodies, the Fc portion may be mutated toincrease or decrease effector function using techniques known in theart. For example, the deletion or inactivation (through point mutationsor other means) of a constant region domain may reduce Fc receptorbinding of the circulating modified antibody thereby increasing tumorlocalization. In other cases it may be that constant regionmodifications consistent with the instant invention moderate complementbinding and thus reduce the serum half-life and nonspecific associationof a conjugated cytotoxin. Yet other modifications of the constantregion may be used to modify disulfide linkages or oligosaccharidemoieties that allow for enhanced localization due to increased antigenspecificity or flexibility. The resulting physiological profile,bioavailability and other biochemical effects of the modifications, suchas tumor localization, biodistribution and serum half-life, may easilybe measured and quantified using well know immunological techniqueswithout undue experimentation.

In certain embodiments, an Fc domain employed in an antibody disclosedherein is an Fc variant. As used herein, the term “Fc variant” refers toan Fc domain having at least one amino acid substitution relative to thewild-type Fc domain from which said Fc domain is derived. For example,wherein the Fc domain is derived from a human IgG1 antibody, the Fcvariant of said human IgG1 Fc domain comprises at least one amino acidsubstitution relative to said Fc domain.

The amino acid substitution(s) of an Fc variant may be located at anyposition (i.e., any EU convention amino acid position) within the Fcdomain. In one embodiment, the Fc variant comprises a substitution at anamino acid position located in a hinge domain or portion thereof. Inanother embodiment, the Fc variant comprises a substitution at an aminoacid position located in a CH2 domain or portion thereof. In anotherembodiment, the Fc variant comprises a substitution at an amino acidposition located in a CH3 domain or portion thereof. In anotherembodiment, the Fc variant comprises a substitution at an amino acidposition located in a CH4 domain or portion thereof.

The antibodies disclosed herein may employ any art-recognized Fc variantwhich is known to impart an improvement (e.g., reduction or enhancement)in effector function or FcR binding. Said Fc variants may include, forexample, any one of the amino acid substitutions disclosed inInternational PCT Publications WO88/07089A1, WO96/14339A1, WO98/05787A1,WO98/23289A1, WO99/51642A1, WO99/58572A1, WO00/09560A2, WO00/32767A1,WO00/42072A2, WO02/44215A2, WO02/060919A2, WO03/074569A2, WO04/016750A2,WO04/029207A2, WO04/035752A2, WO04/063351A2, WO04/074455A2,WO04/099249A2, WO05/040217A2, WO05/070963A1, WO05/077981A2,WO05/092925A2, WO05/123780A2, WO06/019447A1, WO06/047350A2, andWO06/085967A2 or U.S. Pat. Nos. 5,648,260; 5,739,277; 5,834,250;5,869,046: 6,096,871: 6,121,022; 6,194,551; 6,242,195: 6,277,375;6,528,624; 6,538,124; 6,737,056; 6,821,505; 6,998,253; and 7,083,784,each of which is incorporated by reference herein. In one exemplaryembodiment, an antibody disclosed herein may comprise an Fc variantcomprising an amino acid substitution at EU position 268 (e.g., H268D orH268E). In another exemplary embodiment, an antibody disclosed hereinmay comprise an amino acid substitution at EU position 239 (e.g., S239Dor S239E) or EU position 332 (e.g., 1332D or 1332Q).

In certain embodiments, an antibody disclosed herein may comprise an Fcvariant comprising an amino acid substitution which alters theantigen-independent effector functions of the antibody, in particularthe circulating half-life of the antibody. Such antibodies exhibiteither increased or decreased binding to FcRn when compared toantibodies lacking these substitutions, therefore, have an increased ordecreased half-life in serum, respectively. Fc variants with improvedaffinity for FcRn are anticipated to have longer serum half-lives, andsuch molecules have useful applications in methods of treating mammalswhere long half-life of the administered antibody is desired. e.g., totreat a chronic disease or disorder. In contrast, Fc variants withdecreased FcRn binding affinity are expected to have shorter half-lives,and such molecules are also useful, for example, for administration to amammal where a shortened circulation time may be advantageous. e.g. form vivo diagnostic imaging or in situations where the starting antibodyhas toxic side effects when present in the circulation for prolongedperiods. Fc variants with decreased FcRn binding affinity are also lesslikely to cross the placenta and, thus, are also useful in the treatmentof diseases or disorders in pregnant women. In addition, otherapplications in which reduced FcRn binding affinity may be desiredinclude those applications in which localization the brain, kidney, orliver is desired. In one exemplary embodiment, the altered antibodiesdisclosed herein exhibit reduced transport across the epithelium ofkidney glomeruli from the vasculature. In another embodiment, thealtered antibodies disclosed herein exhibit reduced transport across theblood brain barrier (BBB) from the brain, into the vascular space. Inone embodiment, an antibody with altered FcRn binding comprises an Fcdomain having one or more amino acid substitutions within the “FcRnbinding loop” of an Fc domain. The FcRn binding loop is comprised ofamino acid residues 280-299 (according to Kabat numbering). Exemplaryamino acid substitutions which altered FcRn binding activity aredisclosed in International PCT Publication No. WO05/047327 which isincorporated by reference herein. In certain exemplary embodiments, theantibodies, or fragments thereof, disclosed herein comprise an Fc domainhaving one or more of the following substitutions: V284E, H285E, N286D,K290E and S304D (Kabat numbering).

In other embodiments, antibodies, for use in the diagnostic andtreatment methods described herein have a constant region, e.g., an IgG1or IgG4 heavy chain constant region, which is altered to reduce oreliminate glycosylation. For example, an antibody disclosed herein mayalso comprise an Fc variant comprising an amino acid substitution whichalters the glycosylation of the antibody. For example, said Fc variantmay have reduced glycosylation (e.g., N- or O-linked glycosylation). Inexemplary embodiments, the Fc variant comprises reduced glycosylation ofthe N-linked glycan normally found at amino acid position 297 (EUnumbering). In another embodiment, the antibody has an amino acidsubstitution near or within a glycosylation motif, for example, anN-linked glycosylation motif that contains the amino acid sequence NXTor NXS. In a particular embodiment, the antibody comprises an Fc variantwith an amino acid substitution at amino acid position 228 or 299 (EUnumbering). In more particular embodiments, the antibody comprises anIgG1 or IgG4 constant region comprising an S228P and a T299A mutation(EU numbering).

Exemplary amino acid substitutions which confer reduce or alteredglycosylation are disclosed in International PCT Publication No.WO05/018572, which is incorporated by reference herein. In certainembodiments, the antibodies, or fragments thereof, disclosed herein aremodified to eliminate glycosylation. Such antibodies, or fragmentsthereof may be referred to as “agly” antibodies, or fragments thereof,(e.g. “agly” antibodies). While not being bound by theory, it isbelieved that “agly” antibodies, or fragments thereof; may have animproved safety and stability profile in vivo. Exemplary aglyantibodies, or fragments thereof, comprise an aglycosylated Fc region ofan IgG4 antibody which is devoid of Fc-effector function therebyeliminating the potential for Fc mediated toxicity to the normal vitalorgans that express PAI-1. In yet other embodiments, antibodies, orfragments thereof, disclosed herein comprise an altered glycan. Forexample, the antibody may have a reduced number of fucose residues on anN-glycan at Asn297 of the Fc region, i.e., is afucosylated. In anotherembodiment, the antibody may have an altered number of sialic acidresidues on the N-glycan at Asn297 of the Fc region.

iii) Covalent Attachment

Anti-PAI-1 antibodies disclosed herein may be modified, e.g., by thecovalent attachment of a molecule to the antibody such that covalentattachment does not prevent the antibody from specifically binding toits cognate epitope. For example, but not by way of limitation, theantibodies, or fragments thereof, disclosed herein may be modified byglycosylation, acetylation, pegylation, phosphorylation, amidation,derivatization by known protecting/blocking groups, proteolyticcleavage, linkage to a cellular ligand or other protein, etc. Any ofnumerous chemical modifications may be carried out by known techniques,including, but not limited to specific chemical cleavage, acetylation,formylation, etc. Additionally, the derivative may contain one or morenon-classical amino acids.

Antibodies, or fragments thereof, disclosed herein may further berecombinantly fused to a heterologous polypeptide at the N- orC-terminus or chemically conjugated (including covalent and non-covalentconjugations) to polypeptides or other compositions. For example,anti-PAI-1 antibodies may be recombinantly fused or conjugated tomolecules useful as labels in detection assays and effector moleculessuch as heterologous polypeptides, drugs, radionuclides, or toxins. See.e.g., International PCT publication Nos. WO 92/08495; WO 91/14438; WO89/12624; U.S. Pat. No. 5,314,995; and EP 396.387.

Anti-PAI-1 antibodies may be fused to heterologous polypeptides toincrease the in vivo half-life or for use in immunoassays using methodsknown in the art. For example, in one embodiment, PEG can be conjugatedto the anti-PAI-1 antibodies disclosed herein to increase theirhalf-life in vivo. (Leong, S. R., et al., Cytokine 16:106, 2001; Adv. inDrug Deliv. Rev. 54:531, 2002; or Weir et al., Biochem. Soc.Transactions 30:512, 2002).

Moreover, anti-PAI-1 antibodies disclosed herein can be fused to markersequences, such as a peptide to facilitate their purification ordetection. In certain embodiments, the marker amino acid sequence is ahexa-histidine peptide, such as the tag provided in a pQE vector(QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, Calif., 91311), amongothers, many of which are commercially available. As described in Gentzet al., Proc. Natl. Acad. Sci. USA 86:821-824, 1989, for instance,hexa-histidine provides for convenient purification of the fusionprotein. Other peptide tags useful for purification include, but are notlimited to, the “HA” tag, which corresponds to an epitope derived fromthe influenza hemagglutinin protein (Wilson et al., Cell 37:767, 1984)and the “flag” tag.

Anti-PAI-1 antibodies disclosed herein may be used in non-conjugatedform or may be conjugated to at least one of a variety of molecules,e.g., to improve the therapeutic properties of the molecule, tofacilitate target detection, or for imaging or therapy of the patient.Anti-PAI-1 antibodies disclosed herein can be labeled or conjugatedeither before or after purification, when purification is performed. Inparticular, anti-PAI-1 antibodies disclosed herein may be conjugated totherapeutic agents, prodrugs, peptides, proteins, enzymes, viruses,lipids, biological response modifiers, pharmaceutical agents, or PEG.

The present invention further encompasses anti-PAI-1 antibodiesconjugated to a diagnostic or therapeutic agent. The anti-PAI-1antibodies can be used diagnostically to, for example, monitor thedevelopment or progression of a immune cell disorder (e.g., CLL) as partof a clinical testing procedure to, e.g., determine the efficacy of agiven treatment or prevention regimen. Detection can be facilitated bycoupling the anti-PAI-1 antibodies to a detectable substance. Examplesof detectable substances include various enzymes, prosthetic groups,fluorescent materials, luminescent materials, bioluminescent materials,radioactive materials, positron emitting metals using various positronemission topographies, and nonradioactive paramagnetic metal ions. See,for example, U.S. Pat. No. 4,741,900 for metal ions which can beconjugated to antibodies for use as diagnostics according to the presentinvention. Non-limiting examples of suitable enzymes include horseradishperoxidase, alkaline phosphatase, beta-galactosidase, oracetylcholinesterase; non-limiting examples of suitable prosthetic groupcomplexes include streptavidin/biotin and avidin/biotin; non-limitingexamples of suitable fluorescent materials include umbelliferone,fluorescein, fluorescein isothiocyanate, rhodamine,dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; anon-limiting example of a luminescent material includes luminol;non-limiting examples of bioluminescent materials include luciferase,luciferin, and aequorin; and non-limiting examples of suitableradioactive material include 125I, 131I, 111In or 99Tc.

Anti-PAI-1 antibodies for use in the diagnostic and treatment methodsdisclosed herein may be conjugated to cytotoxins (such as radioisotopes,cytotoxic drugs, or toxins) therapeutic agents, cytostatic agents,biological toxins, prodrugs, peptides, proteins, enzymes, viruses,lipids, biological response modifiers, pharmaceutical agents,immunologically active ligands (e.g., lymphokines or other antibodieswherein the resulting molecule binds to both the neoplastic cell and aneffector cell such as a T cell), or PEG.

In another embodiment, an anti-PAI-1 antibody for use in the diagnosticand treatment methods disclosed herein can be conjugated to a moleculethat decreases tumor cell growth. In other embodiments, the disclosedcompositions may comprise antibodies, or fragments thereof, coupled todrugs or prodrugs. Still other embodiments disclosed herein comprise theuse of antibodies, or fragments thereof, conjugated to specificbiotoxins or their cytotoxic fragments such as ricin, gelonin.Pseudomonas exotoxin or diphtheria toxin. The selection of whichconjugated or unconjugated antibody to use will depend on the type andstage of cancer, use of adjunct treatment (e.g., chemotherapy orexternal radiation) and patient condition. It will be appreciated thatone skilled in the art could readily make such a selection in view ofthe teachings herein.

It will be appreciated that, in previous studies, anti-tumor antibodieslabeled with isotopes have been used successfully to destroy tumor cellsin animal models, and in some cases in humans. Exemplary radioisotopesinclude: 90Y, 125I, 131I, 123I, 111In, 105Rh, 153Sm, 67Cu, 67Ga, 166Ho,177Lu, 186Re and 188Re. The radionuclides act by producing ionizingradiation which causes multiple strand breaks in nuclear DNA, leading tocell death. The isotopes used to produce therapeutic conjugatestypically produce high energy alpha- or beta-particles which have ashort path length. Such radionuclides kill cells to which they are inclose proximity, for example neoplastic cells to which the conjugate hasattached or has entered. They have little or no effect on non-localizedcells. Radionuclides are essentially non-immunogenic.

IV. Expression of Anti-PAI-1 Antibodies, or Antigen Binding FragmentsThereof

Following manipulation of the isolated genetic material to provideanti-PAI-1 antibodies disclosed herein as set forth above, the genes aretypically inserted in an expression vector for introduction into hostcells that may be used to produce the desired quantity of the claimedantibodies, or fragments thereof.

In other embodiments the anti-PAI-1 antibodies, or fragments thereof,disclosed herein may be expressed using polycistronic constructs. Insuch expression systems, multiple gene products of interest such asheavy and light chains of antibodies may be produced from a singlepolycistronic construct. These systems advantageously use an internalribosome entry site (IRES) to provide relatively high levels ofpolypeptides disclosed herein in eukaryotic host cells. Compatible IRESsequences are disclosed in U.S. Pat. No. 6,193,980, that is incorporatedby reference herein. Those skilled in the art will appreciate that suchexpression systems may be used to effectively produce the full range ofpolypeptides disclosed in the instant application.

In one embodiment, the host cell line used for antibody expression is ofmammalian origin; those skilled in the art can determine particular hostcell lines which are best suited for the desired gene product to beexpressed therein. Exemplary host cell lines include, but are notlimited to, DG44 and DUXB11 (Chinese Hamster Ovary lines, DHFR minus).HELA (human cervical carcinoma), CVI (monkey kidney line), COS (aderivative of CVI with SV40 T antigen), R1610 (Chinese hamsterfibroblast) BALBC/3T3 (mouse fibroblast), HAK (hamster kidney line),SP2/O (mouse mycloma), HFA-1c1BPT (bovine endothelial cells), RAJI(human lymphocyte), 293 (human kidney). In one embodiment, the cell lineprovides for altered glycosylation, e.g., afucosylation, of the antibodyexpressed therefrom (e.g., PER.C6® (Crucell) or FUT8-knock-out CHO celllines (Potelligent® Cells) (Biowa, Princeton, N.J.)). In one embodimentNS0 cells may be used. CHO cells can be used in certain specificembodiments. Host cell lines are typically available from commercialservices, the American Tissue Culture Collection or from publishedliterature.

In vitro production allows scale-up to give large amounts of the desiredpolypeptides. Techniques for mammalian cell cultivation under tissueculture conditions are known in the art and include homogeneoussuspension culture, e.g. in an airlift reactor or in a continuousstirrer reactor, or immobilized or entrapped cell culture, e.g. inhollow fibers, microcapsules, on agarose microbeads or ceramiccartridges. If necessary or desired, the solutions of polypeptides canbe purified by the customary chromatography methods, for example gelfiltration, ion-exchange chromatography, chromatography overDEAE-cellulose or (immuno-)affinity chromatography.

Genes encoding the anti-PAI-1 antibodies, or fragments thereof,disclosed herein can also be expressed non-mammalian cells such asbacteria or yeast or plant cells. In this regard it will be appreciatedthat various unicellular non-mammalian microorganisms such as bacteriacan also be transformed; i.e. those capable of being grown in culturesor fermentation. Bacteria, which are susceptible to transformation,include members of the enterobacteriaceae, such as strains ofEscherichia coli or Salmonella; Bacillaceae, such as Bacillus subtilis;Pneumococcus; Streptococcus, and Haemophilus influenzae. It will furtherbe appreciated that, when expressed in bacteria, the polypeptides canbecome part of inclusion bodies. The polypeptides must be Isolated,purified and then assembled into functional molecules.

In addition to prokaryotes, eukaryotic microbes may also be used.Saccharomyces cerevisiae, or common baker's yeast, is the most commonlyused among eukaryotic microorganisms although a number of other strainsare commonly available. For expression in Saccharomyces, the plasmidYRp7, for example, (Stinchcomb et al., Nature. 282:39 (1979); Kingsmanet al., Gene, 7:141 (1979); Tschemper et al., Gene, 10: 157 (1980)) iscommonly used. This plasmid already contains the TRP1 gene whichprovides a selection marker for a mutant strain of yeast lacking theability to grow in tryptophan, for example ATCC No. 44076 or PEP4-1(Jones, Genetics, 85:12 (1977)). The presence of the trp1 lesion as acharacteristic of the yeast host cell genome then provides an effectiveenvironment for detecting transformation by growth in the absence oftryptophan.

V. Pharmaceutical Formulations and Methods of Administration ofAnti-PAI-1 Antibodies

In another aspect, the invention provides pharmaceutical compositionscomprising an anti-PAI-1 antibody, or fragment thereof.

Methods of preparing and administering antibodies, or fragments thereof,disclosed herein to a subject are well known to or are readilydetermined by those skilled in the art. The route of administration ofthe antibodies, or fragments thereof, disclosed herein may be oral,parenteral, by inhalation or topical. The term parenteral as used hereinincludes intravenous, intraarterial, intraperitoneal, intramuscular,subcutaneous, rectal or vaginal administration. The intravenous,intraarterial, subcutaneous and intramuscular forms of parenteraladministration can be used in certain embodiments. While all these formsof administration are clearly contemplated as being within the scopedisclosed herein, a form for administration would be a solution forinjection, in particular for intravenous or intraarterial injection ordrip. Usually, a suitable pharmaceutical composition for injection maycomprise a buffer (e.g. acetate, phosphate or citrate buffer), asurfactant (e.g. polysorbate), optionally a stabilizer agent (e.g. humanalbumin), etc. However, in other methods compatible with the teachingsherein, the polypeptides can be delivered directly to the site of theadverse cellular population thereby increasing the exposure of thediseased tissue to the therapeutic agent.

Preparations for parenteral administration include sterile aqueous ornon-aqueous solutions, suspensions, and emulsions. Examples ofnon-aqueous solvents are propylene glycol, polyethylene glycol,vegetable oils such as olive oil and injectable organic esters such asethyl oleate. Aqueous carriers include water, alcoholic/aqueoussolutions, emulsions or suspensions, including saline and bufferedmedia. In the subject invention, pharmaceutically acceptable carriersinclude, but are not limited to, 0.01-0.1M (e.g. 0.05M) phosphate bufferor 0.8% saline. Other common parenteral vehicles include sodiumphosphate solutions, Ringer's dextrose, dextrose and sodium chloride,lactated Ringer's, or fixed oils. Intravenous vehicles include fluid andnutrient replenishers, electrolyte replenishers, such as those based onRinger's dextrose, and the like. Preservatives and other additives mayalso be present such as for example, antimicrobials, antioxidants,chelating agents, and inert gases and the like. More particularly,pharmaceutical compositions suitable for injectable use include sterileaqueous solutions (where water soluble) or dispersions and sterilepowders for the extemporaneous preparation of sterile injectablesolutions or dispersions. In such cases, the composition must be sterileand should be fluid to the extent that easy syringability exists. Itshould be stable under the conditions of manufacture and storage andwill in an embodiment be preserved against the contaminating action ofmicroorganisms, such as bacteria and fungi. The carrier can be a solventor dispersion medium containing, for example, water, ethanol, polyol(e.g., glycerol, propylene glycol, and liquid polyethylene glycol, andthe like), and suitable mixtures thereof. The proper fluidity can bemaintained, for example, by the use of a coating such as lecithin, bythe maintenance of the required particle size in the case of dispersionand by the use of surfactants. Prevention of the action ofmicroorganisms can be achieved by various antibacterial and antifungalagents, for example, parabens, chlorobutanol, phenol, ascorbic acid,thimerosal and the like. In certain embodiments, isotonic agents areincluded, for example, sugars, polyalcohols, such as mannitol, sorbitol,or sodium chloride in the composition. Prolonged absorption of theinjectable compositions can be brought about by including in thecomposition an agent which delays absorption, for example, aluminummonostearate and gelatin.

In any case, sterile injectable solutions can be prepared byincorporating an active compound (e.g., an antibody by itself or incombination with other active agents) in the required amount in anappropriate solvent with one or a combination of ingredients enumeratedherein, as required, followed by filtered sterilization. Generally,dispersions are prepared by incorporating the active compound into asterile vehicle, which contains a basic dispersion medium and therequired other ingredients from those enumerated above. In the case ofsterile powders for the preparation of sterile injectable solutions, themethods of preparation can be vacuum drying and freeze-drying, whichyields a powder of an active ingredient plus any additional desiredingredient from a previously sterile-filtered solution thereof. Thepreparations for injections are processed, filled into containers suchas ampoules, bags, bottles, syringes or vials, and sealed under asepticconditions according to methods known in the art. Further, thepreparations may be packaged and sold in the form of a kit such as thosedescribed in co-pending U.S. Ser. No. 09/259,337 and U.S. Ser. No.09/259,338 each of which is incorporated herein by reference. Sucharticles of manufacture will in an embodiment have labels or packageinserts indicating that the associated compositions are useful fortreating a subject suffering from, or predisposed to autoimmune orneoplastic disorders.

Effective doses of the stabilized antibodies, or fragments thereof;disclosed herein, for the treatment of the above described conditionsvary depending upon many different factors, including means ofadministration, target site, physiological state of the patient, whetherthe patient is human or an animal, other medications administered, andwhether treatment is prophylactic or therapeutic. Usually, the patientis a human, but non-human mammals including transgenic mammals can alsobe treated. Treatment dosages may be titrated using routine methodsknown to those of skill in the art to optimize safety and efficacy.

For passive immunization with an antibody disclosed herein, the dosagemay range, e.g., from about 0.0001 to 100 mg/kg, and more usually 0.01to 5 mg/kg (e.g., 0.02 mg/kg, 0.25 mg/kg, 0.5 mg/kg, 0.75 mg/kg, 1mg/kg, 2 mg/kg, etc.), of the host body weight. For example dosages canbe 1 mg/kg body weight or 10 mg/kg body weight or within the range of1-10 mg/kg, or in particular embodiments at least 1 mg/kg. Dosesintermediate m the above ranges are also intended to be within the scopedisclosed herein.

Subjects can be administered such doses daily, on alternative days,weekly or according to any other schedule determined by empiricalanalysis. An exemplary treatment entails administration in multipledosages over a prolonged period, for example, of at least six months.Additional exemplary treatment regimens entail administration once perevery two weeks or once a month or once every 3 to 6 months. Exemplarydosage schedules include 1-10 mg/kg or 15 mg/kg on consecutive days, 30mg/kg on alternate days or 60 mg/kg weekly. In some methods, two or moremonoclonal antibodies with different binding specificities areadministered simultaneously, in which case the dosage of each antibodyadministered may fall within the ranges indicated.

Antibodies or fragments thereof, disclosed herein can be administered onmultiple occasions. Intervals between single dosages can be, e.g.,daily, weekly, monthly or yearly. Intervals can also be irregular asindicated by measuring blood levels of polypeptide or target molecule inthe patient. In some methods, dosage is adjusted to achieve a certainplasma antibody or toxin concentration, e.g., 1-1000 ug/ml or 25-300ug/ml. Alternatively, antibodies, or fragments thereof, can beadministered as a sustained release formulation, in which case lessfrequent administration is required. Dosage and frequency vary dependingon the half-life of the antibody in the patient. In general, humanizedantibodies show the longest half-life, followed by chimeric antibodiesand nonhuman antibodies. In one embodiment, the antibodies, or fragmentsthereof, disclosed herein can be administered in unconjugated form. Inanother embodiment, the antibodies disclosed herein can be administeredmultiple times in conjugated form. In still another embodiment, theantibodies, or fragments thereof, disclosed herein can be administeredin unconjugated form, then in conjugated form, or vice versa.

The dosage and frequency of administration can vary depending on whetherthe treatment is prophylactic or therapeutic. In prophylacticapplications, compositions containing the present antibodies or acocktail thereof are administered to a patient not already in thedisease state to enhance the patient's resistance. Such an amount isdefined to be a “prophylactic effective dose.” In this use, the preciseamounts again depend upon the patient's state of health and generalimmunity, but generally range from 0.1 to 25 mg per dose, especially 0.5to 2.5 mg per dose. A relatively low dosage is administered atrelatively infrequent intervals over a long period of time. Somepatients continue to receive treatment for the rest of their lives.

In therapeutic applications, a relatively high dosage (e.g., from about1 to 400 mg/kg of antibody per dose, with dosages of from 5 to 25 mgbeing more commonly used for radioimmunoconjugates and higher doses forcytotoxin-drug conjugated molecules) at relatively short intervals issometimes required until progression of the disease is reduced orterminated, and, in particular embodiments, until the patient showspartial or complete amelioration of symptoms of disease. Thereafter, thepatient can be administered a prophylactic regime.

In one embodiment, a subject can be treated with a nucleic acid moleculeencoding a polypeptide disclosed herein (e.g., in a vector). Doses fornucleic acids encoding polypeptides range from about 10 ng to 1 g, 100ng to 100 mg, 1 ug to 10 mg, or 30-300 ug DNA per patient. Doses forinfectious viral vectors vary from 10-100, or more, virions per dose.

Therapeutic agents can be administered by parenteral, topical,intravenous, oral, subcutaneous, intraarterial, intracranial,intraperitoncal, intranasal or intramuscular means for prophylactic ortherapeutic treatment. Intramuscular injection or intravenous infusioncan be used for administration of an antibody disclosed herein. In somemethods, therapeutic antibodies, or fragments thereof, are injecteddirectly into the cranium. In some methods, antibodies, or fragmentsthereof, are administered as a sustained release composition or device,such as a Medipad™ device.

Agents disclosed herein can optionally be administered in combinationwith other agents that are effective in treating the disorder orcondition in need of treatment (e.g., prophylactic or therapeutic).Additional agents are those which are art recognized and are routinelyadministered for a particular disorder.

Effective single treatment dosages (i.e., therapeutically effectiveamounts) of 90Y-labeled antibodies disclosed herein range from betweenabout 5 and about 75 mCi, and in an embodiment between about 10 andabout 40 mCi. Effective single treatment non-marrow ablative dosages of131I-labeled antibodies range from between about 5 and about 70 mCi, andin an embodiment between about 5 and about 40 mCi. Effective singletreatment ablative dosages (i.e., may require autologous bone marrowtransplantation) of 131 I-labeled antibodies range from between about 30and about 600 mCi, and in an embodiment between about 50 and less thanabout 500 mCi. In conjunction with a chimeric modified antibody, owingto the longer circulating half-life vis-a-vis murine antibodies, aneffective single treatment non-marrow ablative dosages of iodine-131labeled chimeric antibodies range from between about 5 and about 40 mCi.and in an embodiment, less than about 30 mCi. Imaging criteria for,e.g., the 111In label, are typically less than about 5 mCi.

While a great deal of clinical experience has been gained with 131I and90Y, other radiolabels are known in the art and have been used forsimilar purposes. Still other radioisotopes are used for imaging. Forexample, additional radioisotopes which are compatible with the scope ofthe instant invention include, but are not limited to, 123I, 125I, 32P,57Co, 64Cu, 67Cu, 77Br, 81Rb, 81Kr, 87Sr, 113In, 127Cs, 129Cs, 132I,197Hg, 203Pb, 206Bi, 177Lu, 186Re, 212Pb, 212Bi, 47Sc, 105Rh, 109Pd,153Sm, 188Rc, 199Au, 225Ac, 211A 213Bi. In this respect alpha, gamma andbeta emitters are all compatible with in the instant invention. Further,in view of the instant disclosure it is submitted that one skilled inthe art could readily determine which radionuclides are compatible witha selected course of treatment without undue experimentation. To thisend, additional radionuclides which have already been used in clinicaldiagnosis include 125I, 123I, 99Tc, 43K, 52Fc, 67Ga, 68Ga, as well as111In. Antibodies have also been labeled with a variety of radionuclidesfor potential use in targeted immunotherapy (Peirersz et al. Immunol.Cell Biol. 65: 111, 1987). These radionuclides include 188Re and 186Reas well as 199Au and 67Cu to a lesser extent. U.S. Pat. No. 5,460,785provides additional data regarding such radioisotopes and isincorporated herein by reference.

As previously discussed, the antibodies, or fragments thereof, disclosedherein, can be administered in a pharmaceutically effective amount forthe in vivo treatment of mammalian disorders. In this regard, it will beappreciated that the disclosed antibodies, or fragments thereof, will beformulated so as to facilitate administration and promote stability ofthe active agent, and In certain embodiments, pharmaceuticalcompositions in accordance with the present invention comprise apharmaceutically acceptable, non-toxic, sterile carrier such asphysiological saline, non-toxic buffers, preservatives and the like. Forthe purposes of the instant application, a pharmaceutically effectiveamount of an antibody disclosed herein, conjugated or unconjugated to atherapeutic agent, shall be held to mean an amount sufficient to achieveeffective binding to a target and to achieve a benefit, e.g., toameliorate symptoms of a disease or disorder or to detect a substance ora cell. In the case of tumor cells, the polypeptide will in certainembodiments be capable of interacting with selected immunoreactiveantigens on neoplastic or immunoreactive cells and provide for anincrease in the death of those cells. Of course, the pharmaceuticalcompositions disclosed herein may be administered in single or multipledoses to provide for a pharmaceutically effective amount of thepolypeptide.

In keeping with the scope of the present disclosure, the antibodiesdisclosed herein may be administered to a human or other animal inaccordance with the aforementioned methods of treatment in an amountsufficient to produce a therapeutic or prophylactic effect. Thepolypeptides disclosed herein can be administered to such human or otheranimal in a conventional dosage form prepared by combining the antibodydisclosed herein with a conventional pharmaceutically acceptable carrieror diluent according to known techniques. It will be recognized by oneof skill in the art that the form and character of the pharmaceuticallyacceptable carrier or diluent is dictated by the amount of activeingredient with which it is to be combined, the route of administrationand other well-known variables. Those skilled in the art will furtherappreciate that a cocktail comprising one or more species ofpolypeptides according to the present invention may prove to beparticularly effective.

VI. Methods of Treating PAI-1-Associated Disease or Disorders

The anti-PAI-1 antibodies, or fragments thereof, disclosed herein areuseful for antagonizing PAI-1 activity. Accordingly, in another aspect,the invention provides methods for treating PAI-1-associated diseases ordisorders by administering to a subject in need of thereof apharmaceutical composition comprising one or more anti-PAI-1 antibodies,or antigen binding fragments thereof disclosed herein.

PAI-1-associated diseases or disorders amenable to treatment include,without limitation, pathophysiologic conditions such as kidney, liver orlung fibrosis or prevention of abdominal adhesion formation.

The occurrence of intra-abdominal adhesions is a major cause of humanillness. Complications of adhesions may be as serious as alife-threatening bowel obstruction, but chronic pelvic pain andinfertility in women are also common sequelae to peritoneal adhesions.The majority of adhesions is induced by surgery but in some cases alsohas been shown to be caused by inflammation, endometriosis, chemicalperitonitis, radiotherapy, foreign body reaction, and continuousambulatory peritoneal dialysis. Peritoneal damage causes a localinflammatory response that leads to fibrin deposition. It is assumedthat a posttraumatic insufficiency in peritoneal fibrinolytic activity,caused by a decrease in tissue plasminogen activator (tPA) and anincrease in the plasminogen activator inhibitors PAI-1 and PAI-2,permits the deposited fibrin to become organized into permanentadhesions.

Currently available and effective treatment option like Scprafilm® haslimitations for use only in the open access (laparotomy) and cannot beused in the laparoscopy. The search for potential treatment is ongoing.

In certain exemplary embodiments, antibodies disclosed herein may beissued to treat renal fibrosis and associated acute kidney injury aswell as chronic kidney diseases which are the main causes of end-stagerenal failure.

One skilled in the art would be able, by routine experimentation, todetermine what an effective, non-toxic amount of antibody (or additionaltherapeutic agent) would be for the purpose of treating aPAI-1-associated disease or disorder. For example, a therapeuticallyactive amount of a polypeptide may vary according to factors such as thedisease stage (e.g., stage I versus stage IV), age, sex, medicalcomplications (e.g., immunosuppressed conditions or diseases) and weightof the subject, and the ability of the antibody to elicit a desiredresponse in the subject. The dosage regimen may be adjusted to providethe optimum therapeutic response. For example, several divided doses maybe administered daily, or the dose may be proportionally reduced asindicated by the exigencies of the therapeutic situation. Generally,however, an effective dosage is expected to be in the range of about0.05 to 100 milligrams per kilogram body weight per day and in anembodiment from about 0.5 to 10, milligrams per kilogram body weight perday.

The different aspects disclosed herein and their embodiments can becombined with each other. In addition, any of the aspects and theirembodiments described above can be combined with any of the particularaspects and embodiments described herein below.

Some particular aspects and embodiments that further serve to illustratethe present invention are given in the following:

DESCRIPTION OF PARTICULAR ASPECTS AND EMBODIMENTS

-   Claim 1. An isolated monoclonal antibody that binds specifically to    PAI-1, comprising:    -   (a) a heavy chain framework region and a heavy chain variable        region, the heavy chain variable region comprising a heavy chain        CDR1 region comprising SEQ ID NO: 34, a heavy chain CDR2 region        comprising SEQ ID NO: 33, and a heavy chain CDR3 region        comprising SEQ ID NO: 32; and    -   (b) a light chain framework region and a light chain variable        region, the light chain variable region comprising a light chain        CDR1 region comprising SEQ ID NO: 37, a light chain CDR2 region        comprising SEQ ID NO: 145, and a light chain CDR3 region        comprising SEQ ID NO: 35.-   Claim 2. An isolated monoclonal antibody that binds specifically to    PAI-1 comprising:    -   (a) a heavy chain framework region and a heavy chain variable        region comprising SEQ ID NO: 86, and    -   (b) a light chain framework region and a light chain variable        region comprising SEQ ID NO: 93.-   Claim 3. An isolated monoclonal antibody that binds specifically to    PAI-1 comprising:    -   (a) a heavy chain variable region that is at least 95% identical        to the heavy chain variable region of the antibody of claim 2,        and/or    -   (b) a light chain variable region that is at least 95% identical        to the light chain variable region of the antibody of claim 2.-   Claim 4. An isolated monoclonal antibody that binds to essentially    the same epitope as the antibody of claim 1.-   Claim 5. An isolated monoclonal antibody that binds specifically to    PAI-1, comprising:    -   (a) a heavy chain framework region and a heavy chain variable        region, the heavy chain variable region comprising a heavy chain        CDR1 region comprising SEQ ID NO: 34, a heavy chain CDR2 region        comprising SEQ ID NO: 33, and a heavy chain CDR3 region        comprising SEQ ID NO: 32; and    -   (b) a light chain framework region and a light chain variable        region, the light chain variable region comprising a light chain        CDR1 region comprising SEQ ID NO: 37, a light chain CDR2 region        comprising SEQ ID NO: 36, and a light chain CDR3 region        comprising SEQ ID NO: 35.-   Claim 6. The antibody of claim 5, wherein the heavy chain variable    region comprises SEQ ID NO: 6, and the light chain variable region    comprises SEQ ID NO: 7.-   Claim 7. An isolated monoclonal antibody that binds to essentially    the same epitope as the antibody of claim 5.-   Claim 8. A humanized monoclonal antibody that binds specifically to    human PAI-1, wherein the antibody comprises:    -   (a) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 82, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 91, or an antigen-binding fragment        thereof;    -   (b) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 83, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 92, or an antigen-binding fragment        thereof,    -   (c) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 84, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 93, or an antigen-binding fragment        thereof;    -   (d) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 85, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 91, or an antigen-binding fragment        thereof;    -   (e) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 85, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 93, or an antigen-binding fragment        thereof;    -   (f) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 86, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 94, or an antigen-binding fragment        thereof;    -   (g) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 87, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 95, or an antigen-binding fragment        thereof;    -   (h) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 88, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 96, or an antigen-binding fragment        thereof;    -   (i) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 89, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 97, or an antigen-binding fragment        thereof;    -   (j) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 90, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 98, or an antigen-binding fragment        thereof;    -   (l) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 86, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 95, or an antigen-binding fragment        thereof;    -   (m) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 89, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 93, or an antigen-binding fragment        thereof; or    -   (n) a heavy chain having a heavy chain variable region        comprising SEQ ID NO: 89, or an antigen-binding fragment        thereof, and a light chain having a light chain variable region        comprising SEQ ID NO: 95, or an antigen-binding fragment        thereof.-   Claim 9. An isolated monoclonal antibody that binds specifically to    PAI-1, comprising    -   (a) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 22, a heavy chain CDR2 region        comprising SEQ ID NO: 21, and a heavy chain CDR3 region        comprising SEQ ID NO: 20; and a light chain variable region        comprising a light chain CDR1 region comprising SEQ ID NO: 25, a        light chain CDR2 region comprising SEQ ID NO: 24, and a light        chain CDR3 region comprising SEQ ID NO: 23,    -   (b) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 28, a heavy chain CDR2 region        comprising SEQ ID NO: 27, and a heavy chain CDR3 region        comprising SEQ ID NO: 26; and a light chain variable region        comprising a light chain CDR1 region comprising SEQ ID NO: 31, a        light chain CDR2 region comprising SEQ ID NO: 30, and a light        chain CDR3 region comprising SEQ ID NO: 29,    -   (c) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 40, a heavy chain CDR2 region        comprising SEQ ID NO: 39, and a heavy chain CDR3 region        comprising SEQ ID NO: 38; and a light chain variable region        comprising a light chain CDR1 region comprising SEQ ID NO: 43, a        light chain CDR2 region comprising SEQ ID NO: 42, and a light        chain CDR3 region comprising SEQ ID NO: 41,    -   (d) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 46, a heavy chain CDR2 region        comprising SEQ ID NO: 45, and a heavy chain CDR3 region        comprising SEQ ID NO: 44; and a light chain variable region        comprising a light chain CDR1 region comprising SEQ ID NO: 49, a        light chain CDR2 region comprising SEQ ID NO: 48, and a light        chain CDR3 region comprising SEQ ID NO: 47,    -   (e) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 52, a heavy chain CDR2 region        comprising SEQ ID NO: 51, and a heavy chain CDR3 region        comprising SEQ ID NO: 50; and a hght chain variable region        comprising a light chain CDR1 region comprising SEQ ID NO: 55, a        light chain CDR2 region comprising SEQ ID NO: 54, and a light        chain CDR3 region comprising SEQ ID NO: 53,    -   (f) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 58, a heavy chain CDR2 region        comprising SEQ ID NO: 57, and heavy chain CDR3 region comprising        SEQ ID NO: 56; and a light chain variable region comprising a        light chain CDR1 region comprising SEQ ID NO: 61, a light chain        CDR2 region comprising SEQ ID NO: 60, and a light chain CDR3        region comprising SEQ ID NO: 59,    -   (g) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 64, a heavy chain CDR2 region        comprising SEQ ID NO: 63, and a heavy chain CDR3 region        comprising SEQ ID NO: 62; and a light chain variable region        comprising a light chain CDR1 region comprising SEQ ID NO: 67, a        light chain CDR2 region comprising SEQ ID NO: 66, and a light        chain CDR3 region comprising SEQ ID NO: 65,    -   (h) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 70, a heavy chain CDR2 region        comprising SEQ ID NO: 69, and a heavy chain CDR3 region        comprising SEQ ID NO: 68; and a light chain variable region        comprising a light chain CDR1 region comprising SEQ ID NO: 73, a        light chain CDR2 region comprising SEQ ID NO: 72, and a light        chain CDR3 region comprising SEQ ID NO: 71; or    -   (i) a heavy chain variable region comprising a heavy chain CDR1        region comprising SEQ ID NO: 76, heavy chain CDR2 region        comprising SEQ ID NO: 75, and a heavy chain CDR3 region        comprising SEQ ID NO: 74; and a light chain variable region        comprising a light chain CDR1 region comprising SEQ ID NO: 79, a        light chain CDR2 region comprising SEQ ID NO: 78, and a light        chain CDR3 region comprising SEQ ID NO: 77.-   Claim 10. An isolated monoclonal antibody that binds specifically to    PAI-1, that binds to essentially the same epitope on PAI-1 as the    humanized monoclonal antibody of claim 8 or claim 9.-   Claim 11. A method of restoring plasmin generation comprising    administering to a subject in need thereof orally, parenterally by a    solution for injection, by inhalation, or topically a    pharmaceutically effective amount of a PAI-1 antibody.-   Claim 12. The method of claim 11, wherein the method treats a    condition comprising increased levels of fibrotic tissue.-   Claim 13. The method of claim 12, wherein the condition is fibrosis,    skin fibrosis, systemic sclerosis, lung fibrosis, idiopathic    pulmonary fibrosis, interstitial lung disease, chronic lung disease,    liver fibrosis, kidney fibrosis, chronic kidney disease, thrombosis,    venous and arterial thrombosis, deep vein thrombosis, peripheral    limb ischemia, disseminated intravascular coagulation thrombosis,    acute ischemic stroke with and without thrombolysis, or stent    restenosis.-   Claim 14. The method of claim 11, 12, or 13 wherein the PAI-1    antibody comprises the antibody of any of the preceding claims.-   Claim 15. Use of a pharmaceutically effective amount of a PAI-1    antibody for the manufacture of a medicament for treating a    condition caused by increased levels of PAI-1 or increased    sensitivity to PAI-1, comprising administering to a patient orally,    parenterally by a solution for injection, by inhalation, or    topically.

EXAMPLES

The present invention is further illustrated by the following exampleswhich should not be construed as further limiting. The contents ofSequence Listing, Figures and all references, patents and publishedpatent applications cited throughout this application are expresslyincorporated herein by reference.

Furthermore, in accordance with the present invention there may beemployed conventional molecular biology, microbiology, and recombinantDNA techniques within the skill of the art. Such techniques areexplained fully in the literature. See, e.g., Sambrook, Fritsch &Maniatis, Molecular Cloning: A Laboratory Manual, Second Edition (1989)Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (herein“Sambrook et al., 1989”); DNA Cloning: A Practical Approach, Volumes Iand II (D. N. Glover ed. 1985); Oligonucleotide Synthesis (M. J. Gaited. 1984); Nucleic Acid Hybridization [B. D. Hames & S. J. Higgins eds.(1985)]; Transcription And Translation [B. D. Hames & S. J. Higgins,eds. (1984)]; Animal Cell Culture [R. I. Freshney, ed. (1986)];Immobilized Cells And Enzymes [IRL Press, (1986)]; B. Perbal, APractical Guide To Molecular Cloning (1984); F. M. Ausubel et al.(eds.). Current Protocols in Molecular Biology. John Wiley & Sons, Inc.(1994).

Example 1: Hybridoma Generation: Immunization of Mice with PAI-1 Proteinand Antibody Generation

Antibodies were developed that would be cross-reactive to human (h) andcynomolgous (cyno) monkey active PAI-1 (glycosylated or non-glycosylatedform) and that would neutralize the inhibitory activity of PAI-1 andrestore downstream production of plasmin thereby being an effectivetherapeutic for treatment of kidney, liver or lung fibrosis orprevention of abdominal adhesion formation and keloid scar formation.Neutralization of PAI-1 inhibitory function by monoclonal antibodies hasbeen described to fall under three mechanisms: (1) blocking PAI-1 to tPAor uPA by steric hindrance, (2) converting PAI-1 into a latentconformation, or (3) converting PA-1 into a substrate conformation.

a) Antigens

PAI-1 is secreted from the cells in an active conformation stabilized byits binding with subnanomolar affinity to vitronectin. PAI-1 undergoesspontaneous conformational change from active conformation into a latentconformation within minutes at 37° C. and within hours at roomtemperature. Once bound to vitronectin, PAI-1 becomes more resistant tothe conformational change which prolongs the half-life of PAI-1 inactive conformation from minutes to hours. To extend active conformationPAI-1 half-life in the immunized animals and to allow the mouse immunesystem to recognize the active PAI-1 conformation, a complex ofvitronectin and PAI-1 was used for immunizations.

Human glycosylated PAI-1 produced in insect cells was purchased fromInnovative Research (Cat# IGLYHPAI-A). Vitronectin (Cat# IHVN) and tPA(Cat# HTPA-TC) were also purchased from Innovative Research. To produceimmunogens PAI-1 was incubated with vitronectin at a 1:1 molar ratio for1 hour at room temperature, or with tPA at a 1:1 molar ratio for 15minutes at 37° C. All immunogens were prepared using sterile saline asdiluent.

b) Immunizations

Standard hybridoma production protocols known in the art wereimplemented to produce antibodies. Standard approaches previouslydescribed in the literature used PAI-1 only or PAI-1/tPA complex. Theinventors instead generated antibodies against the active conformationof PAI-1. PAI-1/vitronectin complex was used as a novel approach togenerating antibodies to PAI-11. A three-prong strategy, outlined below,was taken to generate antibodies:

-   -   (1) Classical in immunization of mice with PAI-1/vitronectin        complex to obtain mouse splenocytes for fusion with mouse        myeloma cell line as a fusion partner to produce hybridoma;    -   (2) Classical immunization of mice with PAI-1/tPA complex to        obtain mouse splenocytes for fusion with mouse myeloma cell line        as a fusion partner to produce hybridoma; and    -   (3) Classical immunization of mice with PAI-1 only to obtain        mouse splenocytes for fusion with mouse myeloma cell line as a        fusion partner to produce hybridoma.

Three mice per antigen (PAI-1 only, Vn/PAI-1 complex, tPA/PAI-1 complex)were used in the study. The mice were 9-20 week-old naïve female BALB/cMice (Charles River, strain code 028). On day 0, nine mice wereimmunized intraperitoneally with PAI-1 alone, Vn/PAI-1 or tPA/PAI-1complexes in phosphate-buffered saline (PBS). A total of 10 ug ofantigen per mouse was mixed at 1:1 volume to volume ratio of SigmaAdjuvant System (Sigma cat #6322) in a total volume of 200 μl per mouse.On day 14, mice were boosted with the same amount of antigen andprepared the same way as on day 0. On day 21, blood samples werecollected for PAI-1 specific antibody titer evaluation. Mice immunizedwith PAI-1/tPA complexes showed very low specific reactivity againstPAI-1 and high anti-tPA titers and were not used for downstream fusions.

On day 51, the mouse with the highest anti-PAI-1 specific antibody titerand the lowest titer against the protein that PAI-1 was complexed to(i.e., either Vn or tPA) while those having the highest titer againstmouse and rat PAI-1 orthologs were selected for fusion. The miceselected for fusion were boosted with PAI-1 only or PAI-1/Vn complex inPBS as an antigen total of 10 ug per mouse mixed at 1:1 ratio of SigmaAdjuvant System (Sigma cat #6322) in a total volume of 200 μl per mouseas described above. At day 55 mice were sacrificed by CO₂ chamber, bloodwas collected through the cardiac puncture and spleen was harvested forhybridoma production. The other four mice underwent the same procedureat later times (2-4 months after the first mouse was used for fusion).

Serum titrations were performed on three mice for PAI-1 only andPAI-1/tPA and two mice for PAI-1/Vn using the ELISA protocol describedin Example 2 (Binding ELISA).

TABLE 3 Serum Titers for Mouse Immunized with PAI-1, PAI-1/Vn orPAI-1/tPA Serum Titer Against PAI-1 (OD₄₀₅) Immunogen Mouse # OD 1:100OD 1:1000 OD 1:10000 PAI-1 1 2.1 1.9 1 PAI-1 2 2.1 1.4 1 PAI-1 3 2.0 1.41 PAI-1/Vn 2 2.15 1.5 1 PAI-1/Vn 3 1.7 1.25 1 PAI-1/tPA 1 1.2 0.8 0.3PAI-1/tPA 2 1.3 0.9 0.7 PAI-1/tPA 3 1.3 0.9 0.5 NMS n/a 0.4 0.12 0.07NMS = normal mouse serum; n/a = not applicable OD₄₀₅ using BioTekSynergy HT instrument

The mice immunized with PAI-1-tPA complex did not reach high specifictiter criteria and were not used for fusions (Table 3). Based on theserum titers presented in Table 3, a total of 5 mice with high specifictiter against PAI-1 were selected for fusions.

b) Fusions

The five mice having the highest specific titer against PAI-1 wereselected for fusions. On the day of the fusion, the mice were sacrificedin a CO₂ chamber, blood was collected through cardiac puncture and thespleens removed and placed into a Petri dish containing 10 ml of serumfree Hybridoma Fusion Medium (IMDM; Iscove's Modified Dulbecco's Medium500 ml (HyClone SH30259.01). Splenocytes were squeezed out of thefibroelastic coat by forceps and washed twice in 10 ml of serum freeIMDM (including initial spin).

Cells were counted in a Countess Automated Cell Counter. Fusion partnercells (myeloma: FO (ATCC ref CRL-1646)) and splenocytes were thencombined in one 50 ml tube at ratio of 1:2 to 1:10 (by cell number) andspun down at 970 rpm for 10 min (slow spin) to form a loose pellet.Preheated (at 37° C.) 1 ml PEG (PEG 1500 in 75 mM Hepes 50% w/v. Rochecat #783641 (10783641001) was added drop by drop to the cell pellet over1 minute period of time and cells were mixed after every drop of PEG wasadded. The pellet was incubated with PEG for another 1 minute followedby addition of 10 ml of serum-free IMDM medium over 1 minute, such thatthe first 1 ml out of 10 is added over 30 sec. Cells underwent slow spinat 970 rpm for 10 min to preserve viability. Fused cells were plated in96-well plates at 200 ul in selection medium (200 ml Gibco Hybridoma(SFM #12045), 20 ml 10% HyClone SuperLow IgG Defined FBS (# SH30898.03),2 ml penicillin/streptomycin, 4 ml (Hybridoma Fusion and CloningSupplement (Roche Diagnostics 11 363 735 001 (50×)) and 4 ml of HAT(hypoxanthine-aminopterin-thymidine) (Sigma-Aldrich # HO262 (50×)).Fusions were ready for screening about 10 to 14 days later, or whenmedium in the wells turned yellow. Supernatants from the developedhybridomas were then tested by ELISA (Example 2) for the presence ofantibodies binding to PAI-1 and PAI-1/Vn complexes.

Example 2: Binding ELISA for Hybridoma Supernatant Screening forSpecificity to PAI-1-Vitronectin Complex

Each fusion from the spleens of the five mice selected resulted in about5000 clones that needed to be screened for binding to PA-1/Vn complex asa first-step primary screen. Primary screening of the hybridomasupernatants was performed in parallel using ELISA against either PAI-1or PAI-1-Vitronectin complexes to select hybridomas binding specificallyto PAI-1 complexed to Vitronectin. The materials used for the ELISA werethe following: Immulon 4 HBX ELISA plates (Dynax cat # N0541216); humanmonomeric Vitronectin at 5 ug/ml (Innovative Research cat# IHVN);glycosylated human PAI-1 (active form) (Molecular Innovations cat#GLYHPAI-A); non-glycosylated mouse PAI-1 in some fusions (MolecularInnovations cat# MPAI-A); a secondary antibody that was HRP-goatanti-mouse IgG (H+L) (Jackson ImmunoResearch Labs #115-035-166); and,ABTS substrate: Roche Diagnostics (#11 204 521 001).

Control antibodies used were:

-   -   a) 33B8, a mouse monoclonal inhibitory antibody against PAI-1        (IgG1; Innovative Research cat# IMA-33H8);    -   b) 33H1, a mouse monoclonal inhibitory antibody against PAI-1        (IgG1; Innovative Research cat# IMA-33H1);    -   c) 31C9, a mouse monoclonal non-inhibitory antibody against        PAI-1 (IgG1: Innovative Research cat# IMA-31C9); and    -   d) 1B7.11, a IgG1 isotype control antibody (anti-TNP mAb        produced in-house from hybridoma cell line purchased from ATCC        (Cat# TIB-191)

The ELISA method was as follows: plates coated with 5 ug/ml Vn in PBSovernight at 4° C. at 50 ul/well; the next day plates were blocked 1hour with 200 ul 1% bovine serum albumin in PBS (BSA/PBS); plates werewashed four times with 200 ul/well PBS; active PAI-1 at 2 ug/ml in 1%BSA/PBS was added to the plates at 50 ul/well and incubated 1 hour,plates were washed four times with 200 ul/well PBS; antibody dilutionsin 1% BSA/PBS or hybridoma supernatants from the original 96-well plateswere added to ELISA plates at 50 ul/well; plates were incubated 1 hourat room temperature (RT); plates were washed four times with 200 ul/wellPBS: HRP-anti-mouse IgG 50 ul 1:2000 in 1% BSA/PBS was added andincubated 1 hour at room temperature; plates were washed four times with200 ul/well PBS; ABTS substrate (one pill dissolved in 5 ml) at 50ul/well was added to the plates) and then plates were read on BioTekSynergy HT instrument using OD₄₀s. A typical standard curve for antibodytitration in the binding ELISA is shown in FIG. 2. The antibodies 31C9,3318 and 33H1 served as positive controls and IgG1 served as a negativecontrol. Table 4 shows that of the about 5000 clones generated, 675clones were positive for binding to both PAI-1 and PAI-1/Vn. Theseclones were then screened for PAI-1 affinity.

TABLE 4 Number of Clones Positive for Binding to Both PAI-1 and PAI-1/Vn# of Clones Positive for Binding to Fusion Immunogen Mouse # Both PAI-1and PAI-1/Vn A PAI-1/Vn 2 131 B PAI-1 2 146 C PAI-1/Vn 3 145 D PAI-1 3104 E PAI-1 1 149

Example 3: Biacore Screening of Hybridoma Supernatants by AffinityRanking

Further selection of a high affinity antibody with low off-rate wasperformed by Biacore. Biacore hybridoma supernatant screening wasperformed either by: (1) reverse screening using anti-mouse immobilizedanti-PAI-1 antibodies or (2) forward screening assay using free PAI-1 asa ligand or against immobilized Vn.

The instruments used were the BIACORE 2000 or BIACORE 3000 (GEHealthcare), designed for biomolecular interaction analysis (BIA) inreal time. The sensor chip used was the CM5 chip (GE Healthcare) withcarboxymethylated dextran matrix on the surface. Each sensor chip hasfour parallel flow cells (Fc). Every flow cell was coupled withanti-mouse IgG Fc mAb via standard amine coupling according to themanufacture's protocol for chip preparation.

In the Biacore reverse screening assay. ELISA positive hybridomasupernatants were selected and filtered through 0.2 in filters beforebeing injected onto Biacore chip surface. Each hybridoma supernatant wasinjected onto one flow cell of flow cells Fc2-Fc4 and the IgG in thehybridoma supernatant would be captured to the chip surface byanti-mouse IgG Fc mAb, while Fc1 was left alone as reference cells.Human PAI-1 protein in PBS was then injected to Fc1 to Fc4. PBS bufferwas also injected over the chip surface as a blank. After subtractingsignals of Fc1 and blank buffer runs, the binding affinity(KD)/disassociation rate (kd) of the antibody from the supernatants toPAI-1 protein was analyzed and ranked using Scrubber 2 software.

In the Biacore forward screening assay, purified human vitronectinprotein was immobilized to CM5 chip flow cells Fc1 to Fc4. Human or cynoPAI-1 were captured onto all flow cells. Filtered selected hybridomasupernatants then were injected over captured PAI-1 one per flow cell,except Fc1 which was reserved as the reference flow cell. PBS buffer wasalso injected over the chip surface as a blank. After subtractingsignals of Fc1 and blank buffer runs, binding affinity of antibody inhybridoma supernatant to the vitronectin captured PAI-1 was analyzed andranked using Scrubber 2 software (version 2.0a, 2005; BioLogic Software,BioLogic Software Rty Ltd., 116 Blamey Court, Campbell, ACT 2612Australia).

Table 5 shows a selection of positive and negative antibody clones fromthe fusions A. B, C, D and E. Not all data was shown because of thelarge number of antibody clones that were screened. Only the antibodyclones that demonstrated superior (kd<10-⁴ l/s) binding dissociationrate against human and cyno PAI-1 proteins were selected for thefunctional chromogenic assay.

TABLE 5 Hybridoma Supernatant Binding to Human PAI-1 Affinity/ Off RateScreening in Biacore Assay Binding to hPAI-1 Off-rate <= cyno CLONEBinding 10⁻⁴ PAI-1 A9 ND ND ND A20 + − − A37 + − − A39 + + − A41 ND NDND A44 + + + A47 + + + A52 ND ND ND A71 + + + A75 + +/− +/− A83 + +/− −A89 + +/− − A93 + +/− − A98 + − − A99 + + +/− A105 + + + A107 + − −A113 + + + A119 + +/− +/− B16 ND ND ND B18 + − − B28 + + − B29 + − −B32 + + + B58 + + − B85 ND ND ND B89 + + +/− B99 + − +/− B105 + + +/−B109 + + + B118 ND ND ND C26 + − − C45 + + +/− C46 + + + C49 + +/− NDC61 + +/− +/− C66 + − − C69 + + +/− C76 ND ND ND C79 + − − C85 ND ND NDC109 + − − C118 + +/− ND C134 ND ND ND C145 + − +/− D4 − − − D12 + − −D13 − − ND D15 − − ND D31 + − − D33 + +/− − D37 + − − D48 + + +/−D52 + + + E4 + + − E5 + + − E11 + + − E16 + + +/− E20 + ND ND E21 + + −“+” = represents positive binding to h/cPAI-1 or an off-rate of lessthan or equal to 10⁻⁴ “”+/−” = represents partial binding to h/cPAI-1 oran off-rate slightly higher than to 10⁻⁴ “−” = represents low or nobinding to h/cPAI-1 or an off-rate higher than to 10⁻⁴ ND = notdetermined

Example 4: Functional ELISA for Hybridoma Supernatant Screening toSelect for Antibodies that Block the Interaction of PAI-1 with tPA

To allow for selection of functional antibodies, a novel ELISA wasdeveloped to allow distinguishing between antibodies that only bind toPAI-1 versus those antibodies that blocked PAI-1's function as tPAinhibitor (functional ELISA).

Hybridoma supernatants were screened m a novel functional ELISA toidentify hybridoma supernatant from different clones having the abilityto block tPA-PAI-1 interaction. The design of the functional ELISA is asfollows: (1) if the antibody binds to PAI-1 but the antibody bindingdoes not block formation of the covalent bond between PAI-1 and tPA, theanti-tPA antibody will bind to the tPA that is bound to the platethrough PAI-1 and gives a positive readout; (2) if the antibody blocksPAI-1 and thereby blocks the tPA interaction by either changing PAI-1confirmation or by steric hindrance, the anti-tPA antibody will not beable to bind to the plate and readout will be negative (lower OD₄₀₅). Inparallel, hybridoma supernatants were tested for binding to PAI-1 in theELISA described in Example 2. Since the amount of antibody in thehybridoma supernatant is unknown, a lower than control reading (i.e.,below the isotype control reading) was considered to be identifying anantibody of interest. Due to the variable antibody concentration in thesupernatant, blocking in some cases was only partial.

Streptavidin coated plates (NUNC #436014) were incubated for 2 hours atRT with 2 ug/ml biotin-PAI-1 (human PAI-1 having N-terminal biotinlabelled, active fraction; Molecular Innovations cat # NTBIOPAI-A) in 1%BSA/PBS at 50 ul/ml. Plates were blocked 1 hour with 200 ul 1% BSA/PBSat RT and washed four times with 200 ul/well PBS. Purified antibodydilutions and hybridoma supernatants were added to wells at 50 ul/welland incubated for 15 minutes. Plates were washed four times with 200ul/well PBS. Two-chain tPA (Innovative Research cat# HTPA-TC) at 1 ug/mlwas added to the plates at 50 ul/well and incubated for 30 minutes atRT. Plates were washed four times with 200 ul/well PBS. Anti-tPA HRPconjugated antibody (Life Span Technologies, cat#LS-C39721) at 1:3000dilution were added to the plates and incubated for 45 minutes. Plateswere washed four times with 200 ul/well PBS. ABTS substrate (one Tabletdissolved in 5 ml; Roche Diagnostics #11 204 521 001) at 50 ul/well wasadded to the plates and time allowed for color to develop. Plates wereread on BioTek Synergy HT instrument using OD₄₀₅. ODs with the valuesthat are lower than IgG isotype control indicate blocking of tPA bindingto PAI-1.

In some cases functional ELISA was performed prior to Biacoresupernatant screening and served as a selection step that was moreimportant for hybridoma development. A representation curve with 33H1 aspositive control, IgG1 as negative control and A44 as an identifiedpositive antibody clone is shown in FIG. 3.

TABLE 6 Functional ELISA for Hybridoma Supernatant Screening to Selectfor Antibodies that Block the Interaction of PAI-1 with tPA tPA/PAI-1PAI-1 Binding CLONE ELISA Inhibition Selected A9 + − no A20 + − noA37 + + yes A39 + +/− yes A41 + + yes A44 + + yes A47 + + yes A52 + − noA71 + + yes A73 + − no A75 + + yes A83 + + yes A89 + + yes A93 + − noA98 + + yes A99 + − no A105 + + yes A107 + + yes A113 + + yes A119 + +yes B16 + − no B18 + + yes B28 + +/− yes B29 + + yes B32 + + yes B58 + +yes B85 + − no B89 + + yes B99 + + yes B105 + + yes B109 + + yesB118 + + yes C26 + + yes C45 + + yes C46 + − no C49 + − no C61 + + yesC66 + + yes C69 + + yes C76 + − no C79 + + yes C85 + − no C109 + + yesC118 + + yes C134 + − no C145 + + yes D4 + − no D12 + + yes D13 + + yesD15 + + yes D31 + + yes D33 + + yes D37 + + yes D44 + + yes D47 + + yesD48 + + yes D52 + + yes D55 + + yes E4 + − no E5 + − no E11 + + yesE16 + + yes E20 + − no E21 + + yes PAI-1 ELISA = a “+” representsbinding to PAI-1 (see Example 2) tPA/PAI-1 Binding Inhibition = a “+”score represents the interaction of tPA with PAI-1 is inhibited; +/− =partial inhibition of the interaction of tPA with PAI-1

Over 200 supernatants were screened. Table 6 shows a selection ofpositive and negative hybridoma supernatants. About 10 hybridomas perfusion showed ability to block PAI-1 from binding to tPA in functionalELISA. Based on the data from the hybridoma supernatants, hybridomaswere selected for sequencing and medium scale antibody production. Eventhough D4 did not bind well to non-glycosylated PAI-1, it was selectedfor purification and sequencing based on its Biacore binding toglycosylated PAI-1. The purified antibodies were further characterizedin Biacore for affinity kinetics, and in chromogenic and cellular assaysfor potency in comparison to the commercially available antibodies.

Example 5: Sequencing by 5′-RACE (Rapid Amplification of cDNA Ends) andMouse Antibody Purification

Antibodies for a specific target generated from a series of fusionscould have the same sequences. By performing antibody gene sequencing atan early stage of antibody generation, any possibly redundant antibodieswere eliminated and the correct antibody gene sequences guided antibodyselection and humanization as well as chimeric antibody construction.

5′-RACE is a procedure for amplification of nucleic acid sequences froma messenger RNA template between a defined internal site and unknownsequences at the 3′ or the 5′ end of the mRNA. This methodology ofamplification with single-sided specificity has been described as“one-sided” PCR or “anchored” PCR. The original variable murineanti-human PAI-1 antibody sequence of the lead antibody was determinedby 5′-RACE cDNA sequencing and confirmed by N-terminal proteinsequencing.

To determine variable heavy (VH) and light chain (VL) IgG sequences,total RNA from hybridoma cells was isolated using RNeasy Mini Kit(QIAGEN, Cat No. 74104) according to the manufacturer's instructions.Briefly, cells (5×106 cells) were lysed in 350 ul of the kit's RLTbuffer followed by capturing total RNAs on spin column. RNA was elutedin the kit's TE buffer and stored on ice.

First-strand cDNA was prepared using SMARTer™ RACE cDNA AmplificationKit (ClonTech, Cat No. 634923). The 5′-RACE protocol was performedaccording to the manufacturer's instructions. VH and VL chain cDNAs wereseparately amplified by polymerase chain reaction (PCR) using the5′-primers supplied with the SMARTer™ kit and the 3′ VH and VL genespecific primers listed below:

Heavy Chain 3′-Primer: (SEQ ID NO: 105) 5′-TATGCAAGGCTTACAACCACA-3′Light Chain 3′-Primer: (SEQ ID NO: 106) 5′-CTCATTCCTGTTGAAGCTCTTGAG-3′

The amplified VH and VL genes were separately cloned into TOP) vectorusing TOPO TA cloning Kit (Invitrogen, Cat No. K4520-01). The procedureswere performed according to the manufacturer's instructions. Totransform bacteria, reaction mixtures were added into competent E. colicells and incubated on ice for 20 minutes. The tubes, which containedthe E. coli cells and the reaction mixture, were heated at 42° C. for 40seconds and added 250 microliters of lit's SOC medium. After incubatingthe E. coli at 370C for 60 minutes with shaking at 300 rpm, the bacteriawere spread on LB agar plate containing 100 micrograms per ml ofampicillin followed by incubating at 37° C., overnight.

Upon confirmation of the inserted VH and VL gene by PCR, five bacteriaclones were selected and propagated in LB broth containing 100micrograms per nil of ampicillin for plasmid DNA preparation. Theplasmid DNAs were isolated using QIAprep Spin Miniprep Kit (QIAGEN, CatNo. 27104) according to manufacturer's instructions. The VH and VL IgGgenes of hybridomas were sequenced by the Sanger method and the CDRswere determined using the Contact definition (MacCallum et al.).

Monoclonal antibodies were produced in CELLine bioreactor flasks (WilsonWolf Manufacturing Corp.; Cat. #CL350 or Cat # CL1000) according to themanufacturer's instructions in serum-free medium (Gibco Cat. #12045) andpurified by Protein A/G chromatography (GE Healthcare Life Sciences,Cat. #28-4083-47 and #28-4082-53). Purified antibodies were furthercharacterized in Biacore for affinity kinetics, and in chromogenic andcellular assays for potency in comparison to the commercially availableantibodies.

Example 6: Functional Chromogenic Assay Using Purified Antibody

Purified antibodies were tested in a chromogenic assay for the abilityto block PAI-1. PAI-1 inhibits tPA function, therefore, antibodies thatblock PAI-1 will result in restoring tPA function. Chromogenic assaysutilize proteolytic enzymes that act on their natural substrates(proteins and peptides) by hydrolyzing one or more peptide bond(s). Thisprocess is usually highly specific in the sense that only peptide bondsadjacent to certain amino acids are cleaved. Chromogenic substrates arepeptides that react with proteolytic enzymes resulting in the formationof color which is quantifiable. Chromogenic substrates are madesynthetically and are designed to possess selectivity similar to that ofthe natural substrate for the enzyme. Attached to the peptide part ofthe chromogenic substrate is a chemical group which when released afterthe enzyme cleavage gives rise to color. The color change can befollowed spectrophotometrically and is proportional to the proteolyticactivity.

A chromogenic assay was used to confirm the ability of the antibody toneutralize PAI-1 function as a tPA inhibitor, tPA is able to release pNAfrom the chromogenic substrate S2288. S228 in solution has no color, butafter being exposed to tPA and subsequent release of pNA, the solutiondevelops a yellow color that can be read at OD₄₀₅. Color formation canbe observed over 2-3 hours to determine kinetics of the enzymaticreaction. PAI-1 is able to block the enzymatic activity of tPA in aconcentration dependent manner.

A two-step chromogenic assay was performed. All reagents are at 1 Oxconcentration until the step when they were added to substrate solution.In the first step, PAI-1 potency in tPA inhibition was measured usingthe chromogenic assay (PAI-1 titration with fixed tPA concentration).The PAI-1 titration curve was analyzed to determine IC50 for PAI-1blocking tPA activity. Afterward, the IC80 calculated from the curve wasselected for further antibody interrogation for ability to neutralizePAI-1 blocking function and restore tPA enzymatic activity. Equalvolumes (25 ul) of tPA (at 14 nM) (Innovative Research. Cat. No.IHTPA-TC) and glycosylated (active form) human PAI-1 (MolecularInnovations, Cat. No. GLYHPAI-A) or non-glycosylated (active form) mousePAI-1 (Molecular Innovations Cat. # IMPAI) were combined and incubatedusing 3-fold serial dilutions of PAI-1 starting at 108 nM and fixedconcentration of tPA. All protein dilutions were made with 1% BSA/PBS.The mixture was incubated in the wells of a 96-well microtiter plate for15 minutes at room temperature. Then 200 ul chromogenic substrate 82288(1.25 mM) (Chromogenix, Cat. No. S-820852) diluted according tomanufacturer's instructions is added to the wells and OD₄₀₅, absorbancechange at 405 nm over 2 hours every 10 minutes is recorded to measurethe residual tPA activity. For controls, background was measured in theabsence of tPA (no enzymatic reaction), a positive control was no PAI-1(100% tPA activity) and a negative control was PAI-1 at 10-fold excessof tPA (complete blocking of tPA activity). See FIG. 4 forrepresentative curves for 33B8, A44, 33H1 and IgG1.

For the second step, the functional properties of the antibodies weredetermined by assessing their ability to inhibit active PAI-1 andrestore tPA function utilizing the PAI-1 neutralization assay. For thisstep, active PAI-1 12.5 ul (at 56 nM) was incubated with an equal volumeof either PBS (Invitrogen, Cat. No. 14190-144) containing 1% BSA (Sigma,Cat. No. A3059) or with serial 3-fold dilutions of antibody starting at2 uM. Control and unknown antibodies were incubated at concentrations (5fold dilutions) ranging from 0.1 to 300 nM with 3 nM PAI-1 and tPA wasadded to the mixture. All the ingredients were incubated at 10×concentration at room temperature and further diluted 10 fold with tPAsubstrate S2288 which upon cleavage by tPA changes color from clear toyellow. Samples were read at OD 405 for 2 hours every 10 minutes at 37°C. The mixture was allowed to react in the wells of a 96-well microtiterplate for 30 minutes at room temperature to achieve antibody-antigencomplex formation. Then 25 ul of tPA (at 14 nM which corresponds to IC₈₀inhibition of tPA activity) was added to the wells and incubated for 15minutes at room temperature. Finally, 200 ul 1.25 mM substrate S2288diluted according to manufacturer's instructions was added to the mix.The absorbance change at 405 nm is recorded to measure the residual tPAactivity for 2 hours every 10 min. One hundred percent PAI-1 activity isdefined as the PAI-1 activity observed in the absence of antibody.Neutralization of PAI-1 activity by the antibody is calculated from theresidual PAI-1 activity measured in the presence of the antibody.Controls were IgG1 as an isotype control (negative) and 33H1 mAb and33B8 mAb as positive controls. See FIG. 5 for representative curves forB28. E16. E21, A75 and IgG1.

Orthologs of human PAI-1 inhibiting human tPA were tested in the twostep chromogenic assay system. Titration of orthologs was performed asdescribed above for human PAI-1 (see FIG. 6 for representative curves oftitrations) and tPA activity was determined by chromogenic method (seeFIG. 7 for representation curves for 33R8 and A44 against cyno and mousePAI-1). Final concentration of human tPA used in the assay was 1.4 nM.12.5 ul active PAI-1 (56 nM) was incubated with an equal volume ofeither PBS containing 1% BSA or with serial 3-fold dilutions of antibodystarting at 2 uM. The mixture was allowed to react in the wells of a96-well microtiter plate for 30 minutes at room temperature. Then 25 ulof tPA(14 nM) was added to the wells and incubated for 15 minutes atroom temperature. To finalize reaction 200 ul tPA substrate S2288(Chromogenix) (1.25 mM) was added to the mixture. Ortholog PAI-1 wasobtained from Molecular Innovations: mouse PAI-1 (wild type activefraction; cat# MPAI); rat PAI-1 (wild type active fraction: cat# RPAI);and rabbit PAI-1 (stable mutant; cat# RbPAI-191L) cyno PAI-1 (activecyno PAI-1) was produced in-house in E. coli. Because of the pooroff-rates of the rabbit and rat orthologs in the Biacore screening (datanot shown), screening of the antibodies against these orthologs was notperformed.

TABLE 7 Activity of Antibodies against Orthologs and GlycosylationStates of PAI-1 in Functional Chromogenic Assay PAI-1 Ortholog andGlycosylation Status non-gly gly non-gly non-gly Clone ID Isotype hPAI-1hPAI-1 cPAI-1 mPAI-1 A37  IgG1 +/− − − − A39  IgG1 − +++ − − A41  IgG1+/− − − − A44  IgG1 +++ +++ +++ − A47  IgG1 nd − − − A71  IgG1 +++ ++++++ − A75  IgG2a +++ +++ +++ − A83  IgG1 nd +/− +/− − A89  IgG2b − − − −A98  IgG1 nd nd nd nd A105 IgG1 +++ +++ +++ − A107 IgG1 +/− − − − A113IgG1 − − − − A119 IgG2a − − − − B18  IgG1 + + + − B28  IgG2b − +++ − −B29  IgG1 − − − − B32  IgG1 nd − − − B58  IgG1 nd + + − B89  IgG1 nd − −− B99  IgG2a nd + + − B105 IgG1 − − − − B109 IgG1 +++ +++ +++ − B118IgG1 + + + − C26  IgG1 ++ ++ ++ + C45  IgG2b +++ +++ +++ − C61 IgG1 + + + − C66  IgG1 + + + − C69  IgG1 ++ ++ ++ − C79  IgG2b +/− +/−+/− − C109 IgG2b +/− +/− +/− − C118 IgG1 ++ ++ ++ − C145 IgG2b ++ ++ ++− D4   IgG2a + ++ + − D12  IgG1 + + + − D13  IgG1 − − − − D15 IgG1 + + + − D31  IgG1 ++ ++ ++ − D33  IgG1 − − − − D37  IgG2a − − − −D48  IgG2a − +/− − − D52  IgG1 + + + − E11  IgG1 ++ ++ ++ − E16  IgG1+++ +++ +++ − E21  IgG2b +++ +++ +++ − h = human, c = cynomolgousmonkey, m = mouse, nd = not determined “−“ = no activity, “+/−“ =partial activity’ “+” = slight activity, “++” = moderate activity, “+++”= strong activity

One or more antibodies from each fusion demonstrated ability to blockboth cyno and human PAI-1 inhibitory function in this assay, with about14 antibodies having moderate to strong blocking activity. A39 and B28had a unique profile in that these two antibodies blocked glycosylatedhPAI-1 but had no activity against human or cyno non-glycosylated PAI-1.None of the antibodies were able to block mouse PAI-1 activityefficiently (within 10 fold of the human PAI-1) except for C26.

Example 7: Mechanism of Action for Monoclonal Antibodies

Monoclonal antibodies can inhibit PAI-1 by three different mechanisms:a) by steric hindrance, b) by converting PAI-1 into a latentconformation upon binding, and c) by converting PAI-1 into a substratefor tPA conformation instead of the inhibitor (“substrateconformation”). PAI-1 makes a covalent bond with tPA upon interactionwith scrine protease.

The chromogenic assay and SDS-PAGE techniques were used to identifyantibody mechanism of action. A reaction between monoclonal antibody (orcontrol antibodies), PAI-1 and tPA was carried out as described abovefor the functional chromogenic assay. Samples were mixed with Laemmlisample buffer and loaded on SDS-PAGE gel under non-reducing conditionsand ran for 30 minutes. Afterwards, the gels were stained with Coomassieblue to visualize proteins, complexes and the cleaved form of PAI-1.Control monoclonal antibodies with known mechanism of action were usedas comparators. 3388 is known to convert PAI-1 into a latentconformation and 33H1 is known to convert PAI-1 into a substrateconformation. This assay could positively identify the substrateconformation but was unable to distinguish between latent conformationor steric hindrance. Representative SDS-gels are shown in FIGS. 8, 9 and10.

TABLE 8 Mechanism of Action of Monoclonal Antibodies Antibody Mechanismof Action A44 Converts PAI-1 from Active → Substrate Conformation C26Converts PAI-1 from Active → Substrate Conformation C45 Converts PAI-1from Active → Substrate Conformation E21 Converts PAI-1 from Active →Substrate Conformation A39 Converts PAI-1 from Active → LatentConformation or Steric Hindrance B109 Converts PAI-1 from Active →Latent Conformation or Steric Hindrance E16 Converts PAI-1 from Active →Latent Conformation or Steric HindranceA44, C26, C45 and E21 block PAI-1 activity by converting PAI-1 form theactive conformation to the substrate conformation. A39 and B109 have adifferent mechanism of action, but the assay was unable to distinguishwhether these antibodies block PAI-1 activity by changing PAI-1 from theactive conformation to the latent conformation or by steric hindrance.

Example 8: Purified Antibody Binding Kinetics

In kinetics measurement, the antibodies were evaluated in reverse at 25°C. In the reverse assay. PAI-1 antibodies were captured to theanti-mouse IgG Fc antibody surface prepared on CM5 chip followed byinjecting the serial 2× dilutions of PAI-1 proteins (human or cyno)starting at 40 nM. A high flow rate was chosen at 50 ul/mm to avoid masstransportation limitation. Two thousand seconds was allowed fordissociation time to accommodate for the slow off rate of the selectedantibodies. The chip was regenerated by glycine-HCl. pH 1.7 buffer aftereach round of antibody-PAI-1 binding. Kinetics data analysis wasperformed using Biacore BIAevaluation software. The sensorgrams weredouble-referenced by subtracting the reference flow cell values and theblank buffer values. The sensorgrams were fitted by using the simulatedkinetics 1:1 (Langmuir) model with local Rmax. The data for theantibodies tested are shown below in Table 9.

TABLE 9 Binding Kinetics by Biacore Reverse Assay human PAI-1 cyno PAI-1Dissociation Affinity KD Dissociation Affinity KD Antibody Rate kd (1/s)(M) Rate kd (1/s) (M) A39  7.09E−05 1.16E−11 ND ND A44  1.49E−053.76E−12 <= 1.0E−6 <= 1.0E−13 A75  4.76E−04 1.20E−10 ND ND A105 1.64E−044.23E−11 ND ND B28  4.61E−04   6.5E−10 ND ND ND = not determined

Binding kinetics of representative antibodies were further analyzed andcompared in Biacore forward assay with vitronectin and PAI-1 complex. Inthe forward assay, human vitronectin protein was immobilized onto theCM5 chip in flow cells Fc1-Fc4 by amine coupling. Human PAI-1 was thencaptured to the vitronectin surface in flow cells Fc2-Fc4 as ligand. Fc1was reserved as reference cell. The antibodies were diluted 2× startingfrom 40 nM and injected to Fc1-4. Kinetics data analysis was performedusing Biacore BIAevaluation software. The sensorgrams were firstdouble-referenced by subtracting the reference cell values and the blankbuffer values, and then fitted by 1:1 (Langmuir) model was used withglobal Rmax.

TABLE 10 Kinetics of A44 binding to human vitronectin captured humanPAI-1 in Biacore forward assay kd (1/s) KD (M) A44 binding to Vn <=1.0E−6 <= 1.0E−12 captured hPAI-IData in Table 10 indicated that A44 binds free human PAI-1 as well asPAI-1 in vitronectin complex.

Example 9: Functional Assay in Primary Human Cells

To further investigate each antibody's ability to restore downstreamplasmin production by primary human cells, a plasmin generation assaywas used. Only antibodies that showed high potency in the chromogenicassay and good affinity in Biacore were used tested in this assay.

On day 1, human primary hepatic stellate cells (Sciencell CA, cat noSC5300) were plated at 20000 cells/well in starvation medium (DMEMGibco+glutamax-1 4.5 g/L D-Glucose, Pyruvate (31966-021), 0.2% FetalBovine Serum gold PAA (All 1-152)) at 37° C. under 5% CO2. On day 2, toneutralize PAI-1 activity, antibodies were pre-incubated withrecombinant PA-1 (Molecular Innovation, cat# IGLYHPAI-A, recombinantGlycosylated human PAI-1, final concentration 5 nM) for 15 minutes atmorn temperature. At the same time, tPA (Molecular Innovations (cat#HTPA-TC), 5 nM in DMEM without red phenol) was incubated with cells for15 minutes at 37° C. After washing unbound tPA, PAI-1/mAb mixtures wereadded on the cells and then residual tPA activity was measured by addingand glu-Plasminogen/Substrate mixture (Glu-Pg: Sigma cat#9001-91-6; 0.5μM final concentration) and plasmin chromogenic substrate: (CBS00.65Stago cat #00128, 0.5 mM final concentration).

Plasminogen activation to plasmin is detected by kinetic reading every45 seconds of A405/492 nm using spectrophotometer (IEMS, Thermofisher)thermostated at 37° C. Biolisc software (Thermofischer) calculates themaximal rate of chromogenic substrate cleavage: plasmin generationexpressed as Vmax: maximal rate of A405/492 nm per min (mDO/min)calculated. PAI-1 inhibition is then calculated with tPA alone asreference (100% inhibition) and PAI-1 (without mAb, as no inhibition)and plotted using Biostat speed software to calculate IC₅₀ and Imax.

TABLE 11 Plasminogen Generation in Human Primary Hepatic Stellate CellsAntibody IC_(50abs) mean ± sem (nM) I_(max) mean (%) n A44  3.32 ± 0.3497 7 A39  5.4 ± 0.8 99 3 A71  8.61 ± 3.6  90 3 A75  22.6 ± 8.2  66 4A105  27 ± 7.8 88 3 B28  7.28 ± 2.7  90 3 B109 6.11 ± 0.88 94 3 C26 Inactive n/a 2 C45   6.5 ± 1.11 97 4 E16  4.74 ± 2.27 95 3 E21  Inactiven/a 3 33H1 22.92 ± 12   56 3 33B8 Inactive n/a 3 n/a = not applicable

Example 10: Antibody Binding Epitope Exploration by Biacore CompetitionAssay

A selected group of anti-PAI-1 antibodies with superior binding andblocking activities were explored for their potential binding epitopesin Biacore competition assays. In the assays, the newly identifiedantibodies as well as several commercially available anti-PAI-1antibodies with known binding site on human PAI-1 were set up to competefor binding to human PAI-1 protein. Each antibody was immobilized onto aflow cell in Biacore CM5 chip using standard amine coupling reaction.All tested antibodies except for clone H2g retained binding siteactivity after amine coupling. Human PAI-1 protein was captured to theimmobilized antibody on the chip followed by injection of each antibodyas analyte. Only the analyte antibodies that have different bindingsites on human PAI-1 from the immobilized antibody will show additionalbinding signals in Biacore. The competition experiments were repeatedtwice for each immobilized antibody and the results are show in thefollowing Table.

TABLE 12 Summary of Binding Epitopes from Biacore competition assayAnalyte Antibody 33H1 33B8 A44 31C9 A71 A75 B109 B28 C45 C26 E16 E21Immobilized 33H1 c/c b/c b/b b/b b/b b/b b/b b/b b/b c/c b/b b/cAntibody 33B8 b/b c/c b/b b/c b/b b/b b/b p/b b/b b/b b/b b/b A44 b/bb/b c/c b/b b/b b/b b/b b/b c/c b/b c/c b/b 31C9 nt nt nt nt nt nt nt ntnt nt nt nt A71 b/b b/c b/b b/b c/c c/c b/b b/b b/b b/b b/b b/b A75 b/bp/p b/b p/p c/c c/c b/b b/b b/b b/b b/b b/b B109 b/b c/c b/b b/b b/b b/bc/c c/c b/b b/b b/c b/b B28 — — — — — — — — — — — — C45 b/b p/b c/c b/bb/b b/b b/b b/b c/c b/b b/b b/b C26 b/c p/c b/b b/b b/b b/b b/b b/c b/bc/c b/b c/c E16 b/b p/b b/c b/b b/b p/b b/b b/c b/b b/b c/c b/b E21 b/cb/c b/b b/c b/c b/b b/b b/c b/b b/c b/b c/c p = partial binding by theanalyte antibody, c = competition by the analyte antibody, b = bindingby the analyte antibody; ”—“ = no PAI-1 binding to the immobilizedantibody; nt = not tested

When A44 is immobilized and binds PAI-1, C45 (analyte antibody) isunable to bind to PAI-1 that is bound by A44. Therefore, C45 competesfor the same binding site that A44 binds on PAI-1 (denoted in Table 12as “c/c”) or A44 binding to PAI-1 interferes with C45 binding to PAI-1.This analysis is confirmed when the experiment is repeated in thereverse older. Specifically, when C45 is the immobilized antibody and isbound to PAI-1, A44 as the analyte antibody is unable to bind the PAI-1that is bound to C45 (denoted in Table 12 as “c/c”). In a similaranalysis, A71 and A75 compete for the same site on PAI-1. The Biacoreanalysis confirmed that A44 and C45, as well as A71 and A75, competewith or to interfere with each other when binding to PAI-1.

Conversely, the commercially available antibodies, 33H1 and 33B, do notcompete with A44. When A44 is the immobilized antibody and is bound toPAI-1, both 33H1 and 33B8 are able to still bind to the PAI-1 that isbound to A44 (denoted as “b/b” in Table 12). This is confirmed in thereverse experiment. When PAI-1 is bound to immobilized 33H1 orimmobilized 33H8, A44 is still able to bind to PAI-1. Thus, thecommercial antibodies 33H1 and 33B8 do not compete with or interferewith A44 binding to PAI-1.

Interestingly, some immobilized antibodies (i.e., B109) blocked analyteantibody (i.e., 3388) from binding to the captured PAI-1 protein: but,when switching the positions of the immobilized antibody to the analyteantibody (e.g., flipping the pair on the chip), the antibody pair nolonger competed for binding with each other to PAI-1. For example, whenB109 was the immobilized antibody bound to PAI-1, 33B8 was unable tobind PAI-1. However, when 33B8 was the immobilized antibody bindingPAI-1, B109 was able to bind PAI-1. One possible explanation for thisresult is that when the immobilized antibody is bound to PAI-1, PAI-1may shift to an unfavorable conformation for the second or analyteantibody and prevents the analyte antibody from binding (for instance,when B109 is the immobilized antibody and 33B8 is the analyte antibody).However, when the antibody pair is reversed, the immobilizing antibodymay bind in such a manner that PAI-1 conformation is relativelyunchanged, thus allowing the analyte antibody to bind to the bound PAI-1(i.e., the analyte antibody B109 is able to bind PAI-1 that is bound bythe immobilized antibody 3388). Therefore, the competition observedbetween 33B8 and B109 was not due to overlapping binding sites on PAI-1but likely due to a conformational change in PAI-1 when bound to B109.

Another interesting observation was that B28 lost binding to human PAI-1when immobilized via amine coupling, suggesting B28's CDR regionsinvolve amino acids with primary amine group(s).

Example 11: Selection of Mouse Monoclonal Antibody for Humanization

Table 13 shows a summary of the in vitro data characterizing the mostactive monoclonal antibodies from the five fusions performed. Based onthese data, A44 was selected for humanization because A44 was the mostpotent antibody in the chromogenic assay and in plasmin generation whilehaving the highest affinity in Biacore.

TABLE 13 Summary of Monoclonal Antibody Affinity and Potency againstHuman Glycosylated PAI-1 Plasmin Chromogenic Generation Affinity KdMechanism Antibody Assays (nM) (nM) (M) of Action A39 (IgG1/k) 1.70,1.00 5.4 1.16E−11 SH or latent A44 (IgG1/k) 1.66, 1.50, 1.70 3.324.20E−14 substrate A71 (IgG1/k) Approx. 4.00 8.61 ND SH or latent A75(IgG2a/k) 3.00 22.6 1.20E−10 SH or talent A105 (IgG1/k) 7.00 27.04.20E−11 SH or latent B28 (IgG2b/k) 1.80 7.28  6.5E−10 SH or latent B109(IgG1/k) 0.23 6.11 ND SH or latent C26 (IgG1/k) 5.00 Inactive NDsubstrate C45 (IgG2b) 0.5 10.6 ND substrate E16 (IgG1) 1.1 4.74 ND SH orlatent E21 (IgG2b) 1.3 216.0 ND substrate SH = steric hindrance; ND =not determined

The heavy and light chain sequences shown in Table 1 are aligned in FIG.12 and CDRs, as defined by IMGT, are highlighted in bold. Based on thein vitro data presented in the Table 13. A44 was selected forhumanization.

Example 12: Engineering of the Anti-PAI-1 A44 Fab: Humanization,Stabilization and Mutation of Unwanted Sequence Motifs

Several approaches discussed below were taken to humanize, stabilize andoptimize the sequence motifs of the A44 murine antibody against PAI-1.

1) Humanization

The humanization protocol used has been described in PCT/US08/74381(US20110027266), herein incorporated by reference in its entirety. Thevariable light (VL) and variable heavy (VH) sequences of murine A44 wereused to build a homology model of anti-PAI-1 A44 light chain (IC) andheavy chain (HC) in Molecular Operating Environment (MOE; v. 2010.10;Chemical Computing Group). The following templates were used: lightchain framework—1D5I (94% identity in the framework regions), heavychain framework 3KSO (96% identity in the framework regions). L1—1D5I(94% identity), L2—1D5I (94% identity), L3—1AXS (72% identity). H1—1IC7(82% identity), H2—1MBU (68% identity) and H3—2WDB (62% identity). TheH3 loop was particularly difficult to model since Trp is the firstresidue. 2WDB, although a shorter loop, also has a Trp at the beginningof the loop and the same Phe-Asp-Tyr sequence at the end of the H3 loop.The side-chains of Glu-105 (LC) and His-99 were rebuilt and thesubsequent model was energy minimized using the standard proceduresimplemented in MOE. A molecular dynamics (MD) simulation of theminimized 3D homology model of the murine A44 was subsequentlyperformed, with constraints on the protein backbone at 500 K temperaturefor 1.1 nanoseconds (ns) in Generalized Born implicit solvent. Tendiverse conformations were extracted from this first MD run every 100picoseconds (ps) for the last 1 ns. These diverse conformations werethen each submitted to a MD simulation, with no constraints on theprotein backbone and at 300 K temperature, for 2.3 ns. For each of the10 MD runs, the last 2,000 snapshots, one every ps, from the MDtrajectory were then used to calculate, for each murine A44 amino acid,its root mean square deviations (rmsd) compared to a reference medoidposition. By comparing the average rmsd on the 10 separate MD runs of agiven amino-acid to the overall average rmsd of all A44 murineamino-acids, one decides if the amino-acid is flexible enough, as seenduring the MD to be considered as likely to interact with T-cellreceptors and responsible for activation of the immune response. 37amino-acids were identified as flexible in the murine A44 antibody,excluding the CDR and its immediate 5 Å vicinity.

The motion of the 62 most flexible murine A44 amino acids, during the 20ns (10×2 ns), were then compared to the motion of the correspondingflexible amino-acids of 49 human germline homology models, for each ofwhich were run the 10×2 ns MD simulations. The 49 human germline modelswere built by systematically combining the 7 most common human germlinelight chains (vk1, vk2, vk3, vk4, vlambda1, vlambda2, vlambda3) and 7most common human germline heavy chains (vh1a, vh1b, vh2, vh3, vh4, vh5,vh6). The vk1-vh2 human germline antibody showed 0.58 4D similarity ofits flexible amino-acids compared to the flexible amino-acids of themurine A44 antibody; the vk1-vh2 germline antibody was therefore used tohumanize A44 antibody focusing on the flexible amino-acids. Thevlambda3-vh4 human germline showed the second highest 4D similarity,0.57, and was also used as the basis for humanization of the A44antibody. For the pair wise amino-acid association between murine A44and vk1-vh2 amino-acids, the 2 sequences were aligned based on theoptimal 3D superposition of the alpha carbons of the 2 correspondinghomology models. The pair wise amino-acid association between murine A44and vlambda3-vh4 was performed in a similar manner. FIG. 13 shows thealignment of murine A44 light chain with vk1 and vlambda3. FIG. 14 showsthe alignment of murine A44 heavy chain with vh2 and vh4.

2) Stabilization

a) Knowledge-Based Approach

The amino-acids of the light and heavy chains with low frequency ofoccurrence vs. their respective canonical sequences, excluding the CDRs,were proposed to be mutated into the most frequently found amino-acids(ΔΔGth>0.5 kcal/mol; (E. Monsellier, H. Bedouelle. J. Mol. Biol. 362,2006, p. 580-593)). This first list of consensus mutations for the LCand HC has been restricted to the amino-acids found in the closest humangermline (vk1-vh2). Suggested changes in the immediate vicinity of theCDRs (5 Angstroms “Vernier” zone (J. Mol. Biol. 224, 1992, p. 487-499))were removed from consideration. This resulted in two stabilizingmutations in the LC (see Table 15) and five stabilizing mutations in theHC (see Table 16). Other criteria were taken into account to considerthese mutations for potentially stabilizing the anti-PAI-1 A44 antibody.These criteria were a favorable change of hydropathy at the surface or amolecular mechanics based predicted stabilization of the mutant. Also,additional stabilizing mutations reported to be successful in theliterature (E. Monsellier & H. Bedouelle, J. Mol. Biol., 362, 2006, p.580-593; B. J. Steipe et al. J. Mol. Biol, 1994, 240, 188-192) and wereconsidered (see Tables 17 & 18), however, no additional mutations weresuggested.

TABLE 15 Stabilizing Changes Proposed in Light Chain Residue ProposedChange Calculated ΔΔGth Accept Change Lys-3 Val 2.23998 No—not ingermline Met-1l Leu 0.766432 Already changed in humanization Tyr-12 Ser2.04389 Already changed in humanization Leu-36 Val 2.17091 No—VernierLys-42 Gln 0.939652 No—not in germline Thr-46 Leu 2.01966 No—VernierGln-69 Thr 2.16357 No—Vernier Tyr-80 Ala 2.92454 Already changed inhumanization Met-83 Leu 2.57007 Already changed in humanization Gly-84Ala 0.597822 Yes Ile-85 Thr 1.27255 Yes

TABLE 16 Stabilizing Changes Proposed in Heavy Chain Residue ProposedChange Calculated ΔΔGth Aceept Change Glu-1 Gln 0.562423 Yes Met-2 Val3.41361 No—Vernier Glu-6 Gln 0.655069 No—Not in germline Pro-9 Ala0.505324 No—Not in germline Ser-10 Glu 2.40018 Already changed inhumanization Gln-16 Ala 1.11244 No—Not in germline Thr-17 Ser 1.79135No—Not in germline Leu-18 Val 0.760243 No—Not in germline Ser-19 Lys1.20539 No—Not in germline Thr-21 Ser 1.3289 No—Not in germline Ser-23Lys 1.82798 No—Not in germline Val-24 Ala 1.35286 No—Not in germlineThr-25 Ser 1.72008 Yes Ile-37 Val 1.66985 No—Not in germline Arg-38 Lys0.568427 No—Not in germline Lys-39 Gln 2.27769 Yes Phe-40 Arg 1.81199No—Not in germline Asn-43 Lys 1.42568 Already changed in humanizationLys-44 Gly 2.01606 Already changed in humanization Tyr-47 Trp 2.62805 NoVernier Met-48 Ile 1.67766 No Vernier Pro-61 Glu 1.08569 No Not ingermline Ser-62 Lys 0.840485 No Not in germline Leu-63 Phe 1.25428 NoNot in germline Arg-66 Lys 0.528008 No Not in germline Ile-67 Ala1.93707 No—Vernier Ser-68 Thr 1.36475 Yes Ile-69 Leu 0.550185 No—VernierArg-71 Val 0.61536 No—Vernier Asn-72 Asp 3.40632 Yes Thr-73 Lys 0.5597No—Vernier Lys-75 Ser 0.81321 No—Not in germline Asn-76 Ser 0.744463No—Not in germline Gln-77 Thr 1.30652 No—Not in germline Tyr-78 Ala2.54699 No—Vernier Val-85 Leu 1.71111 No Not in germline Thr-87 Ser1.30394 No Not in germline Thr-90 Ser 0.557686 No—Not in germline Thr-92Val 1.13795 No—Not in germline

TABLE 17 Combinations of stabilizing mutations evaluated AdditionalAccept Combination* changes suggested Change L1 (40->P & 42->Q)None—neither changed No changes L2 (45->K) None—already K45 None L3(74->T) None—already T74 None L4 (76->S) None—already S76 None L5(84->A, 85->T) None—already changed in None stabilization H1 (15->G)None—not in germline None H2 (61->E, 62->Lys, 63->Phe) None in germlineNone H3 (86->T, 87->S, 88->E) 87 and 88 not in germline None S1 (L1 &L5) None No S2 (H1 & H3) None No *Note: Sequential numbering used torefer to residues

TABLE 18* Stabilization mutations evaluated Light Chain Residue*Additional changes suggested Accept Change 15->L V15->L No—V15 in Vk1germline 90->Q None already Q90 None 32->Y None—already Y32 None 106->INone—already I106 None 63->S None—already S63 None 21->I None—alreadyM21 None *Note: Sequential numbering used to refer to residues

3D and MD-Based Approaches

3D and MD-based approaches have been previously reported (Seco J., LuqueF. J., Barril X., J. Med. Chem. 2009 Apr. 23:52(8):2363-71; MalinJonsson et al., J. Phys. Chem. B 2003, 107:5511-5518). Hydrophobicregions of the antibody were explicitly identified by analyzing themolecular dynamics simulation of the Fab in a binary solvent (20%isopropanol in water, 20 ns production simulation). Additional analysisusing a hydrophobic surface map within Schrodinger's maestro software(v. 8.5.207) was completed. The protein surface analyzed by these twomethods is quite hydrophilic. Even with both these techniques, noresidues contributing to any hydrophobic patches on the surfaces werepresent therefore, no anti-aggregation mutations were suggested.

3) Humanization by Grafting

Humanization using grafting techniques has previously been reported (P.T. Jones, P. H. Dear, J. Foote, M. S. Neuberger, G. Winter, Nature 1986,321:522-525). The humanization started by identifying the two closesthuman germlines to anti-PAI1 A44 variable domain light and heavy chains.This was done by performing a BLAST search vs. all the human germlineswhich were systematically enumerated (all possible combinations of the V& J domains for the kappa and lambda chains; V, D and J domains for theheavy chains). The BLAST searches were performed using an intranetapplication linked to the Sequence Information Retrieval and Analysis(SIRA) service provide by the National Center for BiotechnologyInformation (NCBI).

The closest human germline were identified with 70% and 67% sequenceidentity to anti-PAI1 A44 variable domain light and heavy chains,respectively. Using the internal VBASE germline sequences, the lightchain was found to be close to V 1-O18 (approximately 64% identity)locus and the heavy chain was close to 4-30 (approximately 69% identity)locus of the VH4 sub-family. CDR regions (based on Kabat) and Vernierresidues are indicated in italics for mA44 light chain (A44LC) and forIGVK1-33-01_IGKJ4-01 (IGVK1). Vernier residues as defined in J. Mol.Biol, 1992, 224, 487 are underlined. The humanizing mutations (inboldface) were obtained by performing a pairwise comparison of the twoaligned sequences, excluding the CDR & Vernier zone residues (alsounderlined in murine) as defined above. T46L and Q691 from the murinelight chain and M2V in the marine heavy chain (Vernier zone residue)were mutated to the predominantly conserved human germline sequence asone part or the humanization by grafting approach (LC5a, HC5a). Inanother variant, these three Vernier zone residues were retained as seenin the original murine sequence (LC5b, HC5b).

mA44-Light Chain (SEQ ID NO: 141) D I K MTQSPSS MYASLGERVT ITCKASQDIN SYLS WL QOKP GKSPK TLIY R ANRSVDGVPS RFS GS G S GQ D  Y SLTISSLEY EDMGIYYCLQ YDEFPPT F GG GTKLEIKIGKV3-11-02_IGKJ4-01 (SEQ ID NO: 143)EIVLTQSPAT LSLSPGERAT LSCRASQSVS SYLAWYQQKP GQAPRLLIYDASNRATGIPA RFSGSGSGRD FTLTISSLEP EDFAVYYCQQ RSNWPLTFGG GTKVEIKmA44-Heavy Chain (SEQ ID NO: 140) E M QLQESGPS LVKPSQTLSL TCSVTG DSMT N..GYWNWIR KFPGNKLE YM   G YIT..YSGS TYYNPSLKGR  I S I T R N T SKN Q YYLQLSSVT TEDTATYYC A   R WHYGSPYYF DY W GQGTYLT VSSIGHV6-1-02_IGHD6-13-01_IGHJ4-02 (SEQ ID NO: 144)QVQLQQSGPG LVKPSQTLSL TCAISGDSVS SNSAAWNWIRQSPSRGLEWL GRTYYRSKWY NDYAVSVKSR ITINPDTSKNQFSLQLNSVT PEDTAVYYCA RGYSSSWYYF DYWGQGTLVT VSS

The next closest human germline was identified with 59% and 58% sequenceidentity to anti-PAI1 A44 variable domain light and heavy chains,respectively. Using the internal VBASE germline, this light chain isfound to be close to VκIII-L6 (˜56% identity) locus and the heavy chainclose to 6-01 locus of the VH6 sub-family. CDR regions (based on Kabat)and Vernier regions and are indicated in italics. Vernier regions (asdefined in. J. Mol. Biol., 1992, 224, 487) and underlined. Thehumanizing mutations were obtained by performing a pairwise comparisonof the 2 aligned sequences, excluding the CDR & Vernier zone residues(also underlined in murine) as defined above and are shown in boldface.

mA44-Light Chain (SEQ ID NO: 141) D I K MTQSPSS MYASLGERVT ITCKASQDIN SYLS WL QOKP GKSPK TLIY R ANRSVDGVPS RFS GS G S GQ D  Y SLTISSLEY EDMGIYYCLQ YDEFPPT F GG GTKLEIKIGKV3-11-02_IGKJ4-01 (SEQ ID NO: 143)EIVLTQSPAT LSLSPGERAT LSCRASQSVS SYLAWYQQKP GQAPRLLIYDASNRATGIPA RFSGSGSGRD FTLTISSLEP EDFAVYYCQQ RSNWPLTFGG GTKVEIKmA44-Heavy Chain (SEQ ID NO: 140) E M QLQESGPS LVKPSQTLSL TCSVTG DSMT N..GYWNWIR KFPGNKLE YM   G YIT..YSGS TYYNPSLKGR  I S I T R N T SKN Q YYLQLSSVT TEDTATYYC A   R WHYGSPYYF DY W GQGTYLT VSSIGHV6-1-02_IGHD6-13-01_IGHJ4-02 (SEQ ID NO: 144)QVQLQQSGPG LVKPSQTLSL TCAISGDSVS SNSAAWNWIRQSPSRGLEWL GRTYYRSKWY NDYAVSVKSR ITINPDTSKNQFSLQLNSVT PEDTAVYYCA RGYSSSWYYF DYWGQGTLVT VSS

4) Mutation of Unwanted Sequence Motifs

The following motifs of sequences were considered: Asp-Pro (acid labilebond), Asn-X-Ser/Thr (glycosylation, X=any amino-acid but Pro),Asp-Gly/Ser/Thr (succinimide/iso-asp formation in flexible regions),Asn-Gly/His/Ser/Ala/Cys (exposed deamidation sites), and Met (oxidationin exposed areas). The VL & VH domains of murine anti-PAI1 A44 possesstwo potential glycosylation sites: N⁵²RS (in CDR2) in the LC and N⁷²TSin the HC. One exposed deamidation site is present in CDR1 of the HC(N³¹G). Three potential sites of succinimide formation were identifiedin the original murine sequence: D⁵⁶G (end of CDR2) in the LC, and D²⁷S(in CDR1) and D⁸⁹T in the HC. The LC problematic motifs, N⁵²RS and D⁵⁶G,are both in CDR2. Since these mutations occur in a CDR, they wereaddressed by mutation in two proposed engineered sequences below (LC2and LC4). N⁵² was conservatively mutated to Gin and D⁵⁶ was mutated to(Glu. There are four existing problematic residues in the HC. The firsttwo occur in CDR1: the potential succinimide formation site, D²⁷S, andthe deamidation site N³¹G. Two additional problematic motifs also occurin the third framework region. In CDR1, D²⁷ was mutated to an E to avoidthe formation of succinimide, while N³¹ was altered to a Q. N⁷² and D⁸⁹were altered to Q and E, respectively. These problematic motifs wereaddressed in engineered sequences HC2a and HC4 described below. The HC2bvariant contains only the mutation of the N³¹G deamidation site.

The resulting humanized sequences were blasted for sequence similarityagainst the IEDB database (found on the world wide web atimmuneepitope.com, version June 2009; Vita R., Zarebeski L., GreenbaumJ. A., Emami H., Hoof I., Salimi N., Damle R., Sette A., Peters B. Theimmune epitope database 2.0 Nucleic Acids Res. 2010. January, 38(Database issue):D854-62. Epub 2009, Nov. 11) to ensure that none of thesequences contain any known human B- or T-cell epitopes (sequenceidentity of 70% used as cut-off for the results obtained through BLASTsearch and considering only the results from human species). DeClerck,et al. (International Publication No. WO 2002034776) have disclosedantibody binding epitopes of PAI-1, none of which are problematic forthe epitopes disclosed herein.

For the murine A44 LC, there is one human epitope from Kirschmann et al.(The Journal of Immunology, 1995, 155, 5655-5662). It possesses ˜71%identity over a 14 amino acid stretch as seen below. The subjectsequence was a partial sequence that had not been verified by massspectrometry. No binding data is reported for this peptide. This epitopewas seen in all the LC variants proposed. No potentially problematicepitopes were identified when a similar search was performed for the HC.

5) Original Sequences of Anti-PAI1 Variable Domains

CDRs are highlighted in bold and Vernier regions are (as defined byFoote & Winter, J. Mol. Biol., 1992, 224:487-499) are underlined.

Light Chain (SEQ ID NO: 142)   1 DIKMTQSPSS MYASLGERVT ITCKASQDIN SYLSWLQQKP GKSPKTLIY R  51ANRSVDGVPS RFSGSGSGQD YSLTISSLEY EDMGIYYCLQ YDEFPPT FGG 101GTKLEIKRAD AAPTVSIF Germinality index =70% with IGKV1-33-01_IGKJ4-01 [VκI-O18] Heavy Chain (SEQ ID NO: 140)   1EMQLQESGPS LVKPSQTLSL TCSVFG DSMT NGYWNWIRKF PGNKLEYMG Y  51ITYSGSTYYN PSLKGRISIT RNTSKNQYYL QLSSVTTEDT ATTTCAR WHY 101 GSPYYFDYWG QGTTLTVSS Germinality index =67% with IGHV4-59-02_IGHD6-137-01_IGHJ-02 [VH4 4-30]

6) Engineered Sequences

4D humanization and grafting approaches were applied to the closest twohuman germline sequences

a) Engineered Light Chain Sequences

LC1a contains seven mutations derived from the 4D humanization methodusing the closest germline sequence, vk1. LC1b has 12 mutations derivedfrom the 4D humanization to the second closest human germline sequence,v13. LC2 contains 2 additional mutations in CDR2 as compared to LC1a.These mutations address a potential glycosylation site (N⁵²RS) and apotential site of succinimide formation (D⁵⁶G). LC3 contains themutations from the 4D humanization to the closest germline sequence withan additional 2 stabilizing mutations. LC4 combines the humanizing,stabilizing and unwanted motif mutations. CDRs and vernier zones are initalics, vernier residues are underlined, humanizing mutations are inboldface, problematic motifs are in double strikethrough and stabilizingmutations are shown in lower case. FIGS. 16 and 17 show summaries of themutations.

LC1a (SEQ ID NO: 91):   1 D I K M TQSPSS LSASVGDRVT ITCKASQDIN SYLS WLQQKP GKSPK TLIY R  51 ANRSVDGVPS RFS G S G S GQ D  YSLTISSLQP EDLGIYYCLQ YDEFPPT F GG 101 GTKLEIKNo additional human epitopes for sequence LC1a found in IEDB database.LC a germinality index=76% with IGKV1-33-01_IGKJ4-01 [VκI-O18].

LC1b (SEQ ID NO: 92):   1 D I K M TQSPSS VSVSPGQTVT ITCKASQDIN SYLS WLQQKP GQSPK TLIY R  51 ANRSVDGVPS RFS G S G S GQ D  YSLTISSLQA MDEGIYYCLQ YEDFPPT F GG 101 GTKLTIKIn addition to the epitope described in section 4 above, K39PGQSPKTLIhas 70% sequence identity to KPGQPPRLLI (Kirschmann et al. J. Immun.,1995, 155, 5655-5662). This peptide is reported to have an IC50>100.000nM against all the HLA-DR alleles for which it was tested. LC1bgerminality index=67% with IGKV1-33-01_IGKJ4-01 [VκI-O18].

LC2 (SEQ ID NO: 93):   1 D I K M TQSPSS LSASVGDRVT ITCKASQDIN SYLS WLQQKP GKSPK TLIY R  51 AQRSVEGVPS RFS G S G S GQ D  YSLTISSLQP EDLGIYYCLQ YDEFPPT F GG 101 GTKLEIKNo additional human epitopes for sequence LC2 were found in IEDBdatabase.LC2 germinality index=76% with IGKV1-33-01_IGKJ4-01 [VκI-O18].

LC3 (SEQ ID NO: 94):   1 D I K M TQSPSS LSASVGDRVT ITCKASQDIN SYLS WLQQKP GKSPK TLIY R  51 ANRSVDGVPS RFS G S G S GQ D  YSLTISSLQP EDLatYYCLQ YDEFPPT F GG 101 GTKLEIKNo additional human epitopes for sequence LC3 were found in IEDBdatabase. LC3 germinality index=78% with IGKV1-33-01_IGKJ4-01 [VκI-O18].

LC4 (SEQ ID NO: 95):   1 D I K M TQSPSS LSASVGDRVT ITCKASQDIN SYLS WLQQKP GKSPK TLIY R  51 AQRSVEGVPS RFS G S G S GQ D  YSLTISSLQP EDLatYYCLQ YDEFPPT F GG 101 GTKLEIKNo additional human epitopes for sequence LC4 were found in IEDBdatabase. LC4 germinality index=78% with IGKV1-33-01_IGKJ4-01 [VκI-O18].

LC5a (SEQ ID NO: 96):   1 D I Q M TQSPSS LSASVGDRVT ITCKASQDIN SYLS WLQQKP GKAPK L LIY R  51 ANRSVDGVPS RFS G S G S G T D  YTFTISSLQP EDIATYYCLQ YDEEPPT F GG 101 GTKVEIKIn addition to the epitope described in section 4 above, A43PKLLIYRANhas 80% sequence identity to APKLLIYAASSL (Kirschmann et al. J. Immun.,1995, 155, 5655-5662). The molecular weight was not determined on thispeptide and no binding data was reported. LC5a germinality index=85%with IGKV1-33-01_IGKJ4-01 [VκI-O18].

LC-5b (SEQ ID NO: 97):   1 D I Q M TQSPSS LSASVGDRVT ITCKASQDIN SYLS WLQQKP GKAPK TLIY R  51 ANRSVDGVPS RFS G S G S GQ D  YTFTISSLQP EDIATYYCLQ YDEFPPT F GG 101 GTKVEIKNo additional human epitopes for sequence LC5b were identified in IEDBdatabase.LC5b germinality index=83% with IGKV1-33-01_IGKJ4-01 [VκI-O18].

LC5c (SEQ ID NO: 98):   1 E I V M TQSPAT LSLSPGERAT LSCKASQDIN SYLS WLQQKP GQAPR TLIY R  51 ANRSVDGIPA RFS G S G S GQ D  YTLTISSLEP EDFAVYYCLQ YDEFPPT F GG 101 GTKVEIKIn addition to the epitope described in section 4 above, K³⁰PGQAPRTLIhas 80% sequence identity to KPGQPPRLLI (Kirschmann et al. J. Immun.,1995, 155, 5655-5662). This peptide is reported to have an IC50>100,000nM against all the HLA-DR alleles for which it was tested. LC5cgerminality index=79% with IGKV3-11-02_IGKJ4-01 [VκIII-L6]. A schematicof all light chain mutations is shown in FIG. 15.

b) Engineered Heavy Chain Sequences

HC1a contains eight mutations derived from the 4D humanization method tothe closest human germline sequence. HC1b contains six mutations derivedfrom the 4D humanization method to the 2^(nd) closest germline sequence.HC2a contains four additional mutations when compared to HC1a to addressunwanted sequence motifs. HC2b only addresses the deamidation site inCDR1 (N³¹G). HC3 contains the humanizing mutations from HC1a with anadditional five stabilizing mutations. HC4 contains humanizing mutationsfrom HC1a, stabilizing mutations from HC3 and the mutations addressingproblematic motifs from HC2a. CDRs and vernier zones are in italics,vernier residues are underlined, humanizing mutations are in boldface,problematic motifs are in double strikethrough and stabilizing mutationsare shown in lower case.

HC1a (SEQ ID NO: 82):   1 E M TLKESGPT LVKPTQTLSL TCSVTG DSMT NGYWNWIRKF PGKALE YMG Y  51 ITYSGSTYYN PSLKGR I S I T  R N T SKNQ YYL TLSSVTTVDT ATYYC AR WHY 101 GSPYYFDY W G QGTTLTVSSNo human epitopes were identified for sequence HC1a in IEDB database.HC1a germninality index=68% with IGHV4-31-03_IGHD6-25-01_IGHJ4-02.

HC1b (SEQ ID NO: 83):   1 E M QLQESGPG LVKPSETLSL TCSVTG DSMT NGYWNWIRKF PGKGLE YMG Y  51 ITYSGSTYYN PSLKGR I S I T  R N T SKNQ YYL KLSSVTTADT ATYYC AR WHY 101 GSPYYFDY W G QGTTLTVSSNo human epitopes were identified for sequence HC1b in IEDB database.HC1b germinality index=73% with IGHV4-31-03_IGHD6-25-01_IGHJ14-02.

HC2a (SEQ ID NO: 84):   1 E M TLKESGPT LVKPTQTLSL TCSVTGESMT  QGYWNWIRKF PGKALE YMG Y  51 ITYSGSTYYN PSLKGR I S I T  RQT SKNQ YYL TLSSVTTVET ATYYC AR WHY 101 GSPYYFDY W G QGTTLTVSSNo human epitopes were identified for sequence HC2a in IEDB database.HC2a germinality index=67% with IGHV4-31-03_IGHD6-25-01_IGHJ4-02.

HC2b (SEQ ID NO: 85):   1 E M TLKESGPT LVKPTQTLSL TCSVTG DSMT QGYWNWIRKF PGKALE YMG Y  51 ITYSGSTYYN PSLKGR I S I T  R N T SKNQ YYL TLSSVTTVDT ATYYC AR WHY 101 GSPYYFDY W G QGTTLTVSSNo human epitopes were identified for sequence HC2b in IEDB database.HC2b germninality index=67% with IGHV4-31-03_IGHD6-25-01_IGHJ4-02.

HC3 (SEQ ID NO: 86):   1 q M TLKESGPT LVKPTQTLSL TCSVsG DSMT NGYWNWIRqF PGKALE YMG Y  51 ITYSGSTYYN PSLKGR ItI T  R d T SKN QYYL TLSSVTTVDT ATYYC AR WHY 101 GSPYYFDY W G QGTTLTVSSNo human epitopes were identified for sequence HC3 in IEDB database. HC3germinality index 72% with IGHV4-31-03_IGHD6-25-01_IGHJ4-02.

HC4 (SEQ ID NO: 87):   1 q M TLKESGPT LVKPTQTLSL TCSVsGESMT  QGYWNWIRqF PGKALE YMG Y  51 ITYSGSTYYN PSLKGR ItI T  RQT SKNQ YYL TLSSVTTV ET ATYYC AR WHY 101 GSPYYFDY W G QGTTLTVSSNo human epitopes were identified for sequence HC4 in IEDB database. HC4germinality index=70% with IGHV4-31-03_IGHD6-25-01_IGHJ4-02.

HC5a (SEQ ID NO: 58):   1 Q V QLQESGPG LVKPSETLSL TCTVS G DSMT NGYWNWIRQP PGKGLE YMG Y  51 ITYSGSTYYN PSLKSR I T I S  R N T SKNQYSL KLSSVTAADT AVYYC AR WHY 101 GSPYYFDY W G QGTLVTVSSNo human epitopes were identified for sequence HC5a in IEDB database.HC5a germinality index=84% with IGHV4-59-02_IGHD6-13-01_IGHJ4-02 [VH44-59].

HC5b (SEQ ID NO: 89):   1 Q M QLQESGPG LVKPSETLSL TCTVS G DSMT NGYWNWIRQP PGKGLE YMG Y  51 ITYSGSTYYN PSLKSR I T I S  R D T SKNQ YSL KLSSVTAADT AVYYC AR WHY 101 GSPYYFDY W G QGTLVTVSSNo human epitopes were identified for sequence HC5b in IEDB database.HC5b germinality index=84% with IGHV4-59-02_IGHD6-13-01_IGHJ4-02 [VH44-59].

HC5c (SEQ ID NO: 90):   1 Q M QLQQSGPG LVKPSQTLSL TCAIS G DSMT NGYWNWIRQS PSRGLE YMG Y  51 ITYSGSTYYA VSVKSR I T I N  R D T SKNQ YSL QLSSVTPEDT AVYYC AR WHY 101 GSPYYFDY W G QGTLVTVSSNo human epitopes were identified for sequence HC5c in IEDB database.HC5c germinality index=78% with IGHV6-1-02_IGHD6-13-01_IGHJ4-02 [VH66-01].A schematic of all heavy chain mutations is shown in FIG. 16.

c) Combinations of Heavy and Light Chain Variant Sequences

For grafting, three versions for the light chain (LC5a. LC5b. LC5c) andthree versions of the heavy chain (HC5a, HC5b, HC5c) were created. LC5acontains 16 mutations derived from grafting to the closest humangermline sequence and retaining the murine CDR and most of the murineVernier zone residues. Two murine Vernier residues. T46 and N69 are notpresent in any human germline sequence and were conservatively mutated.LC5b contains 14 mutations derived from grafting to the closest humangermline sequence and retained the murine CDR and all the murine Vernierzone residues. LC5c contains 22 mutations derived from grafting to thesecond closest human germline sequence and retained the murine CDR andall the murine Vernier zone residues.

HC5a contains 20 mutations derived from grafting to the closest humangermline sequence and retained the murine CDR and most of the murineVernier zone residues with the exception of M2V. Met occurs with a verylow propensity at this position in human germline sequences. HC5bcontains 20 mutations derived from grafting to the closest humangermline sequence and retained the murine CDR and all the murine Vernierzone residues. HC5c contains 23 mutations derived from grafting to thesecond closest human germline sequence and retained the murine CDR andall the murine Vernier zone residues.

Ten combinations were prepared in total (summarized in Table 19):

-   -   LC1a×HC1a (mutations addressing 4D humanization based on the        closest germline sequence)    -   LC1b×HC1b (mutations addressing 4D humanization based on the        2^(nd) closest germline sequence)    -   LC2×HC2a (mutations addressing 4D humanization and unwanted        sequences)    -   LC2×HC2b (mutations addressing 4D humanization and unwanted        sequences)    -   LC1a×HC2b (mutations addressing 4D humanization and unwanted        sequences)    -   LC3×HC3 (mutations addressing 4D humanization and stabilization)    -   LC4×HC4 (mutations addressing 4D humanizing, unwanted sequences        and stabilization)    -   LC5a×HC5a (mutations addressing humanization by grafting        retaining CDRs and incorporating 3 conservative Vernier        modifications)    -   LC5b×HC5b (mutations addressing humanization by grafting        retaining CDRs and Vernier regions)    -   LC5c×HC5c (mutations addressing humanization by grafting        retaining CDRs and Vernier regions)

TABLE 19 Summary of the Ten LC x HC Combinations LC1a LC1b LC2 LC3 LC4LC5a LC5b LC5c (H) (H) (H + UM) (H + S) (H + UM + S) (G) (G) (G) HC1aX(1) (H) HC1b X(2) (H) HC2a X(3)  (H + UM) Low HC2b X(4) X(5)  (H + UM)HC3 X(11) X(6) X(12) (H + S) HC4 X(7)  (H + UM + S) Low HC5a X(S) (G)HC5b X(13) X(14) X(9) (G) HC5c X(10) (G) Low H = humanizing; UM =unwanted motifs; S = stabilizing; G = grafting Low = low expressionlevels Number within the ( ) indicates the variant number; note:variants 11-14 were added following characterization of the original tenvariants (variants 1-10)

TABLE 21 Mutations of the eight LC variants of the anti-PAI1 A44antibody LC Sequential LC1a LC1b LC2 LC3 LC4 LC5a LC5b LC5c Numbering(H) (H) (H − UM) (H + S) (H − UM + S) (G) (G) (G) Asp1 Glu Lys3 Gln GlnVal Ser9 Ala Ser10 Thr Met11 Leu Val Leu Leu Leu Leu Leu Leu Tyr12 SerSer Ser Ser Ser Ser Ser Ser Ala13 Val Leu Leu15 Val Pro Val Val Val ValVal Pro Glu17 Asp Gln Asp Asp Asp Asp Asp Arg18 Thr Val19 Ala Ile21 LeuThr22 Ser Lys42 Gln Gln Ser43 Ala Ala Ala Lys45 Arg Thr46 Leu Asn52 GlnGln Asp56 Glu Glu Val58 Ile Ser60 Ala Gln69 Thr Ser72 Thr Thr Thr Leu73Phe Phe Glu79 Gln Gln Gln Gln Gln Gln Gln Tyr80 Pro Ala Pro Pro Pro ProPro Pro Glu81 Met Met83 Leu Glu Leu Leu Leu Ile Ile Phe Gly84 Ala AlaAla Ala Ala Ile85 Thr Thr Thr Thr Val Leu104 Val Val Val Glu105 ThrNumber of 7 12 9 9 11 16 14 22 mutations H = humanizing; UM = unwantedmotifs; S = stabilizing; G = grafting

TABLE 22 Mutations of the nine HC variants of the anti-PAI1 A44 antibodyHC Sequential HC1a HC1b HC2a HC2b HC3 HC4 HC5a HC5b HC5c Numbering (H)(H) (H − UM) (H − UM) (H + S) (H − UM + S) (G) (G) (G) Glu1 Gln Gln GlnGln Gln Met2 Val Gln3 Thr Thr Thr Thr Thr Glu5 Lys Lys Lys Lys Lys GlnSer10 Thr Gly Thr Thr Thr Thr Gly Gly Gly Ser15 Thr Thr Thr Thr ThrGln16 Glu Glu Glu Ser23 Thr Thr Ala Val24 Ile Thr25 Ser Ser Ser Ser SerAsp27 Glu Glu Asn31 Gln Gln Gln Lys39 Gln Gln Gln Gln Gln Phe40 Pro ProSer Gly42 Ser Asn43 Lys Lys Lys Lys Lys Lys Lys Lys Arg Lys44 Ala GlyAla Ala Ala Ala Gly Gly Gly Asn60 Ala Pro61 Val Leu63 Val Gly65 Ser SerSer Ser68 Thr Thr Thr Thr Thr Thr70 Ser Ser Asn Asn72 Gln Asp Gln AspAsp Tyr79 Ser Ser Ser Gln81 Thr Lys Thr Thr Thr Thr Lys Lys Thr87 AlaAla Pro Glu88 Val Ala Val Val Val Val Ala Ala Asp89 Glu Glu Thr92 ValVal Val Thr114 Leu Leu Leu Leu115 Val Val Val Number of 8 6 12 9 13 1620 20 23 mutations H = humanizing; UM = unwanted motifs; S =stabilizing; G = graftingIn summary, ten variants were generated during the humanization process.These variants were expressed and characterized in several in vitroassays as described below.

7) Characterization of Humanization Variants

Based on the in silico modeling presented in the above example, tenvariants were generated (variants 1-8 by 4D humanization and variants9-10 by CDR grafting; variants 3 and 10 were created on the secondclosest germline). The variable region of the light chain and heavychain DNA of humanized A44 were prepared for HEK293 expression. Proteinswere generated after cloning the corresponding DNA into pXL, plasmids(New England Biolabs; NheI/Eco47III for the HC, NheI/BsiWI for the LC).Humanized sequences were codon optimized for HEK expression and genesynthesized by GeneArt (subsidiary of Life Technologies). The resultingplasmids were co-transfected and transiently expressed in FreeStyle™293Expression System (Invitrogen. Cat#K9000-01). Variants 3 and 10 werevery poorly expressed and were not further pursued. All other variantswere expressed and purified using Protein A columns. Analytical gelsshowed partial glycosylation (about 5-10%) of the light chains invariants 6 and 9 and heavy chains in variants 5 and 7 (data not shown).The remaining eight variants were tested in the chromogenic assay usinghPAI and plasmin generation assay in human stellate cells using humanglycosylated PAI. Results are shown in Table 23.

TABLE 23 Characterization or humanization variants in plasmin generationand chromogenic assay Plasminogen Activation Chromogenic Assay mAb IC50(nM) Y50% IC50 (nM) A44 3.17 45.99 0.44 A44-hv1 3.12 44.99 0.49 A44-hv2Not determined Not determined 0.60 A44-hv4 Inactive 26.00 0.52 A44-hv5Not determined Not determined 1.11 A44-hv6 1.78 56.94 0.82 A44-hv7 Notdetermined Not determined 0.59 A44-hv8 Inactive 11.00 0.76 A44-hv9 1.946.53 0.86

Variants 6 and 9 showed the best potency in the plasmin generation assaybut had partial (5-10%) glycosylation in the light chain. Based on theseresults, new variants 11-14 were produced using combinations of heavychains from variants 6 and 9 and light chains from variants 5 and 7.Table 24 summarizes all the variants created.

TABLE 24 Humanization variants Variant # Description SEQ ID NOs A44-hv1LC1a × HC1a 109 A44-hv2 LC1b × HC1b 110 A44-hv3 LC2 × HC2a 111 A44-hv4LC1a × HC2b 112 A44-hv5 LC2 × HC2b 113 A44-hv6 LC3 × HC3 114 A44-hv7 LC4× HC4 115 A44-hv8 LC5a × HC5a 116 A44-hv9 LC5b × HC5b 117 A44-hv10 LC5c× HC5c 118 A44-hv11 LC2 × HC3 119 A44-hv12 LC4 × HC3 120 A44-hv13 LC2 ×HC5b 121 A44-hv14 LC4 × HC5b 122

TABLE 25 DNA Sequence Humanization variants Gene Protein HC1aGAGATGACCCTGAAAGAGTCCGGCCCCACCC EMTLKESGPTLVKPTQTLSTGGTCAAACCCACCCAGACCCTGAGCCTGAC LTCSVTGDSMTNGYWNWCTGCAGCGTGACCGGCGACAGCATGACCAAC IRKFPGKALEYMGYITYSGGGCTACTGGAACTGGATCCGGAAGTTCCCCG STYYNPSLKGRISITRNTSKGCAAGGCCCTCGAGTACATGGGCTACATCAC NQYYLTLSSVTTVDTATYCTACAGCGGCAGCACCTACTACAACCCCAGC YCARWHYGSPYYFDYWGCTGAAGGGCCGGATCAGCATCACCCGGAACA QGTTLTVSSCCAGCAAGAACCAGTACTACCTGACCCTGTC (SEQ ID NO: 82) CAGCGTG (SEQ ID NO: 123)HC1b GAGATGCAGCTGCAGGAAAGCGGCCCTGGCC EMQLQESGPGLVKPSETLSTGGTCAAACCCAGCGAGACACTGAGCCTGAC LTCSVTGDSMTNGYWNWCTGCAGCGTGACCGGCGACAGCATGACCAAC IRKFPGKGLEYMGYITYSGGGCTACTGGAACTGGATCCGGAAGTTCCCCG STYYNPSLKGRISITRNTSKGCAAGGGCCTCGAGTACATGGGCTACATCAC NQYYLKLSSVTTADTATYCTACAGCGGCAGCACCTACTACAACCCCAGC YCARWHYGSPYYFDYWGCTGAAGGGCCGGATCAGCATCACCCGGAACA QGTTLTVSSCCAGCAAGAACCAGTACTACCTGAAGCTGTC (SEQ ID NO: 83) CAGCGTG (SEQ ID NO: 124)HC2a GAGATGACCCTGAAAGAGTCCGGCCCCACCC EMTLKESGPTLVKPTQTLSTGGTCAAACCCACCCAGACCCTGAGCCTGAC LTCSVTGESMTQGYWNWICTGCAGCGTGACCGGCGAGAGCATGACCCAG RKFPGKALEYMGYITYSGGGCTACTGGAACTGGATCCGGAAGTTCCCCG STYYNPSLKGRISITRQTSKGCAAGGCCCTCGAGTACATGGGCTACATCAC NQYYLTLSSVTTVETATYCTACAGCGGCAGCACCTACTACAACCCCAGC YCARWHYGSPYYFDYWGCTGAAGGGCCGGATCAGCATCACCCGGCAGA QGTTLTVSSCCAGCAAGAACCAGTACTACCTGACCCTGTC (SEQ ID NO: 84) CAGCGTG (SEQ ID NO: 125)HC2b GAGATGACCCTGAAAGAGTCCGGCCCCACCC EMTLKESGPTLVKPTQTLSTGGTCAAACCCACCCAGACCCTGAGCCTGAC LTCSVTGDSMTQGYWNWCTGCAGCGTGACCGGCGACAGCATGACCCAG IRKFPGKALEYMGYITYSGGGCTACTGGAACTGGATCCGGAAGTTCCCCG STYYNPSLKGRISITRNTSKGCAAGGCCCTCGAGTACATGGGCTACATCAC NQYYLTLSSVTTVDTATYCTACAGCGGCAGCACCTACTACAACCCCAGC YCARWHYGSPYYFDYWGCTGAAGGGCCGGATCAGCATCACCCGGAACA QGTTLTVSSCCAGCAAGAACCAGTACTACCTGACCCTGTC (SEQ ID NO: 85) CAGCGTG (SEQ ID NO: 126)HC3 CAGATGACCCTGAAAGAGTCCGGCCCCACCC QMTLKESGPTLVKPTQTLTGGTCAAACCCACCCAGACCCTGAGCCTGAC SLTCSVSGDSMTNGYWNCTGCAGCGTGTCCGGCGACAGCATGACCAAC WIRQFPGKALEYMGYITYGGCTACTGGAACTGGATCCGGCAGTTCCCCG SGSTYYNPSLKGRITITRDGCAAGGCCCTCGAGTACATGGGCTACATCAC TSKNQYYLTLSSVTTVDTCTACAGCGGCAGCACCTACTACAACCCCAGC ATYYCARWHYGSPYYFDCTGAAGGGCCGGATCACCATCACCCGGGACA YWGQGTTLTVSSCCAGCAAGAACCAGTACTACCTGACCCTGAG (SEQ ID NO: 86) CAGCGTG (SEQ ID NO: 127)HC4 CAGATGACCCTGAAAGAGTCCGGCCCCACCC QMTLKESGPTLVKPTQTLTGGTCAAACCCACCCAGACCCTGAGCCTGAC SLTCSVSGESMTQGYWNCTGCAGCGTGTCCGGCGAGAGCATGACCCAG WIRQFPGKALEYMGYITYGGCTACTGGAACTGGATCCGGCAGTTCCCCG SGSTYYNPSLKGRITITRQGCAAGGCCCTCGAGTACATGGGCTACATCAC TSKNQYYLTLSSVTTVETCTACAGCGGCAGCACCTACTACAACCCCAGC ATYYCARWHYGSPYYFDCTGAAGGGCCGGATCACCATCACCCGGCAGA YWGQGTTLTVSSCCAGCAAGAACCAGTACTACCTGACCCTGAG (SEQ ID NO: 87) CAGCGTG (SEQ ID NO: 128)HC5a CAGGTGCAGCTGCAGGAAAGCGGCCCTGGCC QVQLQESGPGLVKPSETLSTGGTCAAACCCAGCGAGACACTGAGCCTGAC LTCTVSGDSMTNGYWNWCTGCACCGTGTCCGGCGACAGCATGACCAAC IRQPPGKGLEYMGYITYSGGGCTACTGGAACTGGATCCGGCAGCCCCCTG STYYNPSLKSRITISRNTSKGCAAGGGCCTCGAGTACATGGGCTACATCACCT NQYSLKLSSVTAADTAVYACAGCGGCAGCACCTACTACAACCCCAGCCT YCARWHYGSPYYEDYWGGAAGTCCCGGATCACCATCAGCCGGAACA QGTLVTVSS CCAGCAAGAACCAGTACAGCCTGAAGCTGAG(SEQ ID NO: 88) CAGCGTG (SEQ ID NO: 129) HC5bCAGATGCAGCTGCAGGAAAGCGGCCCTGGCC QMQLQESGPGLVKPSETLTGGTCAAACCCAGCGAGACACTGAGCCTGAC SLTCTVSGDSMTNGYWNCTGCACCGTGTCCGGCGACAGCATGACCAAC WIRQPPGKGLEYMGYITYGGCTACTGGAACTGGATCCGGCAGCCCCCTG SGSTYYNPSLKSRITISRDTGCAAGGGCCTCGAGTACATGGGCTACATCAC SKNQYSLKLSSVTAADTACTACAGCGGCAGCACCTACTACAACCCCAGC VYYCARWIIYGSPYYFDYCTGAAGTCCCGGATCACCATCAGCCGGGACA WGQGTLVTVSSCCAGCAAGAACCAGTACAGCCTGAAGCTGAG (SEQ ID NO: 89) CAGCGTG (SEQ ID NO: 130)HC5c CAGATGCAGCTGCAGCAGAGCGGCCCTGGCC QMQLQQSGPGLVKPSQTLTGGTCAAACCCAGCCAGACCCTGAGCCTGAC SLTCAISGDSMTNGYWNCTGCGCCATCAGCGGCGACAGCATGACCAAC WIRQSPSRGLEYMGYITYSGGCTACTGGAACTGGATCCGGCAGAGCCCCA GSTYYAVSVKSRITINRDTGCAGAGGCCTCGAGTACATGGGCTACATCAC SKNQYSLQLSSVTPEDTACTACAGCGGCAGCACCTACTACGCCGTGTCC VYYCARWHYGSPYYFDYGTGAAGTCCCGGATCACCATCAACCGGGACA WGQGTLVTVSSCCAGCAAGAACCAGTACAGCCTGCAGCTGAG (SEQ ID NO: 90) CAGCGTG (SEQ ID NO: 131)LC1a GACATCAAGATGACCCAGAGCCCCAGCAGCC DIKMTQSPSSLSASVGDRVTGAGCGCCAGCGTGGGCGACAGAGTGACCAT TTTCKASQDINSYLSWLQQCACATGCAAGGCCAGCCAGGACATCAACAGC KPGKSPKTLIYRANRSVDTACCTGAGCTGGCTGCAGCAGAAGCCCGGCA GVPSRFSGSGSGQDYSLTIAGAGCCCCAAGACCCTGATCTACCGGGCCAA SSLQPEDLGIYYCLQYDEFCCGCAGCGTGGACGGCGTGCCAAGCAGATTT PPTFGGGTKLEIKTCCGGCAGCGGCAGCGGCCAGGACTACAGCC (SEQ ID NO: 91)TGACCATCAGCAGCCTGCAGCCCGAGGACCT GGGCATC (SEQ ID NO: 132) LC1bGACATCAAGATGACCCAGAGCCCCAGCAGCG DIKMTQSPSSVSVSPGQTVTGTCCGTGTCTCCTGGCCAGACCGTGACCATC TITCKASQDINSYLSWLQQACATGCAAGGCCAGCCAGGACATCAACAGCT KPGQSPKTLIYRANRSVDACCTGAGCTGGCIGCAGCAGAAGCCCGGCCA GVPSRFSGSGSGQDYSLTIGTCCCCCAAGACCCTGATCTACCGGGCCAAC SSLQAMDEGIYYCLQYDECGCAGCGTGGACGGCGTGCCAAGCAGATTTT FPPIFGGGTKLTIKCCGGCAGCGGCAGCGGCCAGGACTACAGCCT (SEQ ID NO: 92) GACCATCAGCAGCCTGCAGGCCATGGACGAG GGCATC (SEQ ID NO: 133) LC2GACATCAAGATGACCCAGAGCCCCAGCAGCC DIKMTQSPSSLSASVGDRVTGAGCGCCAGCGTGGGCGACAGAGTGACCAT TITCKASQDINSYLSWLQQCACATGCAAGGCCAGCCAGGACATCAACAGC KPGKSPKTLIYRAQRSVEGTACCTGAGCTGGCTGCAGCAGAAGCCCGGCA VPSRESGSGSGQDYSLTISSAGAGCCCCAAGACCCTGATCTACCGGGCCCA LQPEDLGIYYCLQYDEFPPGCGGAGCGTGGAAGGCGTGCCAAGCAGATTC TFGGGTKLEIKAGCGGCAGCGGCTCCGGCCAGGACTACAGCC (SEQ ID NO: 93)TGACCATCAGCAGCCTGCAGCCCGAGGACCT GGGCATC (SEQ ID NO: 134) LC3GACATCAAGATGACCCAGAGCCCCAGCAGCC DIKMTQSPSSLSASVGDRVTGAGCGCCAGCGTGGGCGACAGAGTGACCAT TITCKASQDINSYLSWLQQCACATGCAAGGCCAGCCAGGACATCAACAGC KPGKSPKTLTYRANRSVDTACCTGAGCTGGCTGCAGCAGAAGCCCGGCA GVPSRFSGSGSGQDYSLTIAGAGCCCCAAGACCCTGATCTACCGGGCCAA SSLQPEDLATYYCLQYDECCGCAGCGTGGACGGCGTGCCAAGCAGATTT FPPTFGGGTKLEIKTCCGGCAGCGGCAGCGGCCAGGACTACAGCC (SEQ ID NO: 94)TGACCATCAGCAGCCTGCAGCCCGAGGACCT GGCCACC (SEQ ID NO: 135) LC4GACATCAAGATGACCCAGAGCCCCAGCAGCC DIKMTQSPSSLSASVGDRVTGAGCGCCAGCGTGGGCGACAGAGTGACCAT TITCKASQDINSYLSWLQQCACATGCAAGGCCAGCCAGGACATCAACAGC KPGKSPKTLIYRAQRSVEGTACCTGAGCTGGCTGCAGCAGAAGCCCGGCA VPSRFSGSGSGQDYSLTISSAGAGCCCCAAGACCCTGATCTACCGGGCCCA LQPEDLATYYCLQYDEFPGCGGAGCGTGGAAGGCGTGCCAAGCAGATTC PTFGGGTKLEIKAGCGGCAGCGGCTCCGGCCAGGACTACAGCC (SEQ ID NO: 95)TGACCATCAGCAGCCTGCAGCCCGAGGACCT GGCCACC (SEQ ID NO: 136) LC5aGACATCCAGATGACCCAGAGCCCCAGCAGCC DIQMTQSPSSLSASVGDRVTGAGCGCCAGCGTGGGCGACAGAGTGACCAT TITCKASQDINSYLSWLQQCACATGCAAGGCCAGCCAGGACATCAACAGC KPGKAPKLLIYRANRSVDTACCTGAGCTGGCTGCAGCAGAAGCCCGGCA GVPSRFSGSGSGTDYTFTIAGGCCCCCAAGCTGCTGATCTACCGGGCCAA SSLQPEDIATYYCLQYDEFCCGCAGCGTGGACGGCGTGCCAAGCAGATTT PPTFGGGTKVEIKTCCGGCAGCGGCTCCGGCACCGACTACACCT (SEQ ID NO: 96)TCACCATCAGCAGCCTGCAGCCCGAGGATAT CGCCACC (SEQ ID NO: 137) LC5bGACATCCAGATGACCCAGAGCCCCAGCAGCC DIQMTQSPSSLSASVGDRVTGAGCGCCAGCGTGGGCGACAGAGTGACCAT TITCKASQDINSYLSWLQQCACATGCAAGGCCAGCCAGGACATCAACAGC KPGKAPKTLIYRANRSVDTACCTGAGCTGGCTGCAGCAGAAGCCCGGCA GVPSRFSGSGSGQDYTFTIAGGCCCCCAAGACCCTGATCTACCGGGCCAA SSLQPEDIATYYCLQYDEFCCGCAGCGTGGACGGCGTGCCAAGCAGATTT PPTFGGGTKVEIKTCCGGCAGCGGCAGCGGCCAGGACTACACCT (SEQ ID NO: 97)TCACCATCAGCAGCCTGCAGCCCGAGGATAT CGCCACC (SEQ ID NO: 138) LC5cGAGATCGTGATGACCCAGAGCCCCGCCACCC EIVMTQSPATLSLSPGERATGTCTCTGAGCCCTGGCGAGAGAGCCACCCT TLSCKASQDINSYLSWLQGAGCTGCAAGGCCAGCCAGGACATCAACAG QKPGQAPRTLIYRANRSVCTACCTGAGCTGGCTGCAGCAGAAGCCCGGC DGIPARFSGSGSGQDYTLTCAGGCCCCCAGAACCCTGATCTACCGGGCCA ISSLEPEDFAVYYCEQYDEACAGAAGCGTGGACGGCATCCCCGCCAGATT FPPTFGGGTKVEIKCAGCGGCAGCGGCTCCGGCCAGGACTACACC (SEQ ID NO: 98)CTGACCATCAGCAGCCTGGAACCCGAGGACT TCGCCGTG (SEQ ID NO: 139) Protein CHASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFEFPPKPKDTLMISRTPEVTCWVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTCLVKGF (SEQ ID NO: 99) CLRTVAAPSVFIFPPSDEQLKSGTASWCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO: 100)All variants, except poorly expressed variants 3 and 10, were tested inBiacore against human and cyno PAI-1 and Vitronectin-PAI-1 complex. Thedata is presented in Table 26.

TABLE 26 Characterization of humanization variants in a BiacoreVitronection Chip/Human PAI-1 mAb/hPAI-1/Vn ka1 (1/Ms) kd 1 (1/s) KD (M)A44 parental* 5.68E+06 2.29E−04 4.04E−11 A44-hv1* 1.10E+07 5.55E−045.26E−11 A44-hv2** 2.99E+06 4.03E−04 1.35E−10 A44-hv4* 4.59E+06 8.80E−051.92E−11 A44-hv5* 2.72E+06 2.76E−05 1.02E−11 A44-hv6* 4.38E+06 5.68E−051.33E−11 A44-hv7** 4.14E+06 3.94E−04 9.64E−11 A44-hv8* n/a n/a n/aA44-hv9* 6.36E+06 1.03E−04 1.70E−11 A44-hv11* 7.66E+06 1.22E−04 1.56E−11A44-hv12* 5.15E+06 8.14E−05 1.61E−11 A44-hv13** 2.40E+06 4.36E−041.79E−10 A44-hv14* 4.06E+06 3.95E−05 9.57E−12 Vitronection Chip/CynoPAI-1 mAb/cPAI-1/Vn ka1 (1/Ms) kd 1 (1/s) KD (M) A44 parental* 3.98E+062.75E−04 6.96E−11 A44-hv1** 3.37E+06 8.27E−03 2.45E−09 A44-hv2**2.30E+06 3.14E−04 1.37E−10 A44-hv4** 2.26E+05 1.70E−04 7.52E−10 A44-hv5*3.40E+06 1.11E−04 3.26E−11 A44-hv6* 5.26E+06 2.51E−05 5.01E−12 A44-hv7**2.50E+06 2.39E−04 9.56E−11 A44-hv8* n/a n/a n/a A44-hv9* 6.51E+061.34E−04 2.15E−11 A44-hv11** 1.56E+06 6.00E−04 3.87E−10 A44-hv12*4.26E+06 2.35E−04 5.69E−11 A44-hv13** 2.12E+06 2.43E−04 1.15E−10A44-hv14* 5.86E+06 2.13E−04 3.86E−11 Anti-human IgG Fc chip/human PAI-1mAb/hPAI-1* ka1 (1/Ms) kd 1 (1/s) KD (M) A44-hv11/hPAI-1 1.57E+066.68E−05 4.25E−11 A44-hv12/hPAI-1 1.62E+06 6.70E−05 4.14E−11A44-hv13/hPAI-1 1.54E+06 2.52E−05 1.64E−11 A44-hv14/hPAI-1 1.25E+063.42E−05 2.70E−11 Anti-human IgG Fc chip/cyno PAI -1 mAb/cPAI-1* ka1(1/Ms) kd 1 (1/s) KD (M) A44-hv11/hPAI-1 1.87E+06 5.60E−05 3.00E−11A44-hv12/hPAI-1 2.24E+06 5.45E−05 2.44E−11 A44-hv13/hPAI-1 1.89E+065.08E−05 2.70E−11 A44-hv14/hPAI-1 2.32E+06 2.69E−05 1.15E−11 n/a meansthe variant did not bind effectively to vitronectin/PAI-1 complex *1:1molecular interaction model **Two state reacbon (conformation change)model

Biacore data did not reveal significant differences between humanizedvariants. All humanized variants, except variant 8, showed affinity toboth cyno PAI-1 and human PAI-1 and PAI-1 complexed to vitronectinwithin an acceptable range. In comparison to parental A44, humanizationdid not appear to change antibody affinity.

Although affinity and potency of the humanized variants didn't differsignificantly in the chromogenic and Biacore assays, the ability of thevariants to restore plasmin generation in the cellular assays wassignificantly lower than parental mouse antibody for some variants (secTable 27 summarizing comparison of chromogenic assay and cellular assaybelow). Humanized variants 11-14 were tested for the ability to blockPAI-1 in the cellular assay.

TABLE 27 Characterization of humanization variants 11-14 in plasmingeneration Plasminogen Activation mAb IC50 (nM) Y50% n A44 3.13 79.79 6A44-hv11 2.01 85.82 6 A44-hv12 1.99 76.70 6 A44-hv13 1.82 71.10 6A44-hv14 1.82 61.22 6 A44-hv9 1.51 50.92 4 A44-hv1 2.08 58.50 2

Variants 11 through 14 showed good potency in the plasmin generationassay and were further characterized in additional in vitro assays.

8) Characterization of Humanization Variants in Human Liver

Additional screening of the humanized variants 11 14 was performed usingendogenously produced human PAI-1 from human plasma and human fibroticliver samples.

PAI-1 activity was evaluated by measuring the ability of this serpin toform a stable complex with urokinase immobilized on 96 well plates.After washing unbound PAI-1, uPA-PAI-1 complexes were detected by theuse of polyclonal antiPAI-1 antibodies. The bound polyclonal anti-PAI-1antibodies (which is proportional to active PAI-1 in the sample) wasthen detected by using a horseradish peroxidase conjugated secondaryantibody (Molecular Innovation Cat. No. HPAIKT). Various concentrationsof A44 humanized variants were incubated for 15 minutes at roomtemperature with either human or cynomolgous recombinant PAI-1 (0.31 nMfinal concentration) and then tested for functional active PAI-1 byuPA-PAI-1 complex using the ELISA described above. Samples were comparedto a human PAI-1 standard. Human plasma from high BMI patients with highactive PAI-1 levels were diluted 4-fold and were incubated withincreasing amounts of A44 humanized variants. Remaining active PAI-1levels were determined using uPA-PAI-1 complex detection by ELISA. Cynorecombinant PAI-1 neutralization was also tested by plasmin generationto confirm cross-reactivity.

TABLE 28 Humanized variant abilty to block endogenous PAI-1 activityhPAI-1 Standard hPlasma TH1782 Cyno PAI-1 IC50 IC50 IC50 (nM) Y50% n mAb(nM) Y50% N (nM) Y50% n 1.31E−01 50.80 2 A44- 1.57E−02 37.50 2 4.24E−0250.80 2 hv11 1.14E−01 53.45 2 A44- 3.35E−03 37.68 2 2.66E−02 53.45 2hv12 1.66E−01 52.82 2 A44- 3.11E−02 61.35 2 2.81E−02 52.82 2 hv135.63E−02 52.47 2 A44- 5.86E−02 73.90 2 2.87E−02 52.47 2 hv14

Human fibrotic liver samples (provided by Biopredic International,Rennes, France from surgical resection of hepatic colon metastasis) werehomogenized as follows: weighed frozen liver samples were homogenized indry tubes containing ceramic beads (Cat No 03961-1-003, BertinTechnology, France) using Precellys homogeniser (Bertin Technology,France; 4° C., 2×30 seconds at 6800 rpm) and then dissolved using 1 ml/gof lysis buffer (NaCl 1.5M in TBS—Tris Buffer Solution 0.1M Tris+0.15MNaCl pH7.4). After centrifugation at 4° C. at 5000 g for 10 min, theliver lysate in the supernatant was harvested and stored frozen at −80°C. Total protein concentration using standard BCA assay and active &total PAI-1 levels (determined by UK-PAI complex ELISA provided by MolInnov Cat No HPAIKT & Cat No MPAIKT-TOT) were performed followingmanufacturer instructions by plotting standard human PAI-1 concentrationvs A450 nm using Biostat Calibration software. Increasing concentrationsof A44 humanized variants incubated with liver lysate diluted to 2.5 nMof active PAI-1 were evaluated as described previously and dataanalyzed. Inhibition of PAI-1 activity (PAI-1 activity without mAb being0% inhibition, no significant and dose-dependent inhibition of PAI-1occurred with IgG1) was calculated for each mAb concentration. Percentinhibition of PAI-1 activity was plotted as a function of mAbconcentration and IC50 was determined Imax using Biostat speed software.Data is shown in FIG. 17 and in Table 29.

TABLE 29 PAI-1 activity neutralization by A44-hv11 in human liver IC50(nM) Imax (%) A44-hv11 (1 nM) 0.0365 99.997 A44-hv11 (2 nM) 0.0503 99.99A44-hv11 (3 nM) 0.0465 99.99 Mean +/− sem 0.0444 +/− 0.004 99.99Based on the above data, A44-hv11 was selected for furthercharacterization in additional structural studies and additional invitro and in vivo studies.

Example 13: Humanization of APG Antibody by Grafting

Humanization using grafting techniques has previously been reported (P.T. Jones, et al., Nature 1986, 321:522-525). The humanization of theanti-PAI1 murine antibody APG began with the murine light chain (SEQ IDNO: 148) and murine heavy chain (SEQ ID NO: 149) from German Patent App.No. DE2000153251; this murine antibody is also described in Debrock etal., Biochimica et Biophysica Acta, 1337(2):257-266 (1997). Identifyingthe germline and canonical classes of the HC and LC chain of the murineantibody yielded muIGHV1-39 and muIGKV14-111, respectively. Next thelist of close human germlines to anti-PAI1 APG variable domain light andheavy chains were identified and ranked by percent identity. Both stepswere done by performing a BLAST search vs. all the human germlines whichwere systematically enumerated (all possible combinations of the V & Jdomains for the kappa and lambda chains; V, D and J domains for theheavy chains). The BLAST searches were performed using theIMGT/DomainGapAlign tool provided at http://www.imgt.org. (SeeEhrenmann, et al. Cold Spring Harbor Protocols 2011.6 (2011)). Theclosest human germlines were identified with 67.4% and 63.3% sequenceidentity to anti-PAI1 APG variable domain light and heavy chains,respectively. Using the IMGT database, the light chain was found to beclose to HuIGKV1-33 and the heavy chain was close to HuIGHV1-46. Theclosest human germline to the anti-PAI1 APG variable domain heavy chainwith a matching canonical class was found to be HuIGHV7-4-1 with asequence identity of 62.2%.

CDR regions (based on a combination of Kabat and IMGT for APG) andVernier residues are indicated in italics for the parent murine APG(mAPG) light chain (SEQ ID NO: 148), IGKV1-33-01_IGKJ4-01 (IGKV1a) (SEQID NO: 107) and for IGKV1-33-01_IGKJ2-02 (IGKV1b) (SEQ ID NO: 150) (seeTable 30, below). Vernier residues as defined in Foote, et al. J. Mol.Biol. 224(2):487-99 (1992) are underlined. The humanizing mutations (inboldface) were obtained by performing a pairwise comparison of the twoaligned sequences, excluding the CDR & Vernier zone residues (alsounderlined m mAPG sequences, Table 30) as defined above. No furtherengineering was performed on the murine APG antibody. These humanizedantibodies were named APGv2 and APGv4.

TABLE 30 APG humanization sequences APG D I K LTQSPSS MYASLGERVT ITCKASQDIY SYLS WF QQKP GKSPK TLIY R Light ChainANRLIDGVPS RFS G S G S GQ D  Y SLTISSLEY EHMGIYYCLQ YEDFPF T FGS GTKLEIK(SEQ ID NO: 148) APG Q V KLQESGPE LVKPGASVKI SCKASG YSFT DYNMNWVKQS KGKSLE WIG I Heavy Chain IHPNAFRRRY NQKFKGK A T L  T V D QSSSTAY LQLNSLTSED SAVYYC AR SK LRFFDYWGQG TTVTVSS (SEQ ID NO: 149)IGKV1-33- DIQMTQSPSS LSASVGDRVT ITCQASQDIS NYLNWYQQKP GKAPKLLIYD01_IGKJ4-01 ASNLETGVPS RFSGSGSGTD FTFTISSLQP EDIATYYCQQ YDNLPLTFGG(IGKV1aa) GTKVEIK (SEQ ID NO: 107) IGKV1-33-01_DIQMTQSPSS LSASVGDRVT ITCQASQDIS NYLNWYQQKP GKAPKLLIYD IGKJ2-02ASNLETGVPS FRSGSGSGTD FTFTISSLQP EDIATYYCQQ YDNLPCSFGQ (IGKV1b) GTKLEIK(SEQ ID NO: 150) IGHV7-4-1-QVQLVQSGSELKKPGASVKVSCKASGYTFTSYAMNWVRQAPGQGLEWM 02_GWINTNTGNPTYAQGFTGRFVFSLDTSVSTAYLQISSLKAEDTAVYYCARx IGHJ4-03xxxxYFDYWGQGTLVTVSS (SEQ ID NO: 151) IGHV1-46-01_QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYYMHWVRQAPGQGLEWM IGHJ4-03GIINPSGGSTSYAQKFGRVTMTRDTSTSTVYMELSSLRSEDTAVYYCARxx xxxYFDYWGQGTLVTVSS(SEQ ID NO: 152) APGv2_VL2 D I Q L TQSPSS LSASVGDRVT ITCKASQDIY SYLS WFQQKP GKAPK TLIY R AN TLIDGVPS RFS G S G S GQ D  YTFTISSLQP EDIATYYCLQ YDEFTFT FGQ GTKLEIK (SEQ ID NO: 153) APGv2_VH2 Q VQLVQSGSE LKKPGASVKV SCKAS G YSF T DYN MNWVRQA PGQGLE WIGI IHPNSGTTTY NQKFKG R A V L  S V D Q SVSTAY LQISSLKAED TAVYYC ARSK LRFFDYWGQG TLVTVSS (SEQ ID NO: 154) APGv2_VH4 Q VQLVQSGAE VKKPGASVKV SCKAS G YSF T DYN MNWVRQAPGQGLEWI GI IHPNSGTT TY NQKFKG R ATL TVD Q STSTAY MELSSLRSED TAVYYC  ARSK LRFFDY WGQG TLVTVSS (SEQ ID NO: 155)

Engineered Sequences

4D humanization and grafting approaches were applied to the humangermline sequence matches described above. For the engineered lightchain sequences, APGv2 contains the murine light chain CDRs grafted intothe human IGKV1-33 germline (APGv2 germinality index=94% withIGKV1-33-01_IGKJ2-01). For the engineered heavy chain sequences, APGv2and APGv4 contain the murine heavy chain CDRs grafted into the humanIGHV7-4-1 and IGHV1-46 germlines respectively (APG_VH2 germinalityindex=91% with IGHV7-4-1-02_IGHD6-25-01_IGHJ4-02; APG_VH4 germinalityindex=91% with IGHV1-46-01_IGHD6-25-01_IGHJ4-02). See Table 30 above.

Combinations of Heavy and Light Chain Variant Sequences

For grafting, one version of the light chain (APGv2_VL2; SEQ ID NO: 153)and two versions of the heavy chain (APGv2_VH2; SEQ ID NO: 154 andAPGv4_VH4; SEQ ID NO: 155) were created. APG_VL2 contains 15 mutationsderived from grafting to the closest human germline sequence andretaining the murine CDR and Vernier zone residues. APG_VH2 contains 21mutations derived from grafting to the closest human germline sequencewith a matching canonical class and retaining the murine CDR and Vernierzone residues. APG_VH4 contains 20 mutations derived from grafting tothe closest human germline sequence and retaining the murine CDR andVernier zone residues. The delimitations of the CDRs for this graftingprotocol are loosely based on the various different definitionsavailable in the literature.

-   -   APG_VL2×APG_VH2 (mutations addressing humanization by grafting        retaining CDRs and Vernier regions)    -   AP(_VL2×APG_VH4 (mutations addressing humanization by grafting        retaining CDRs and Vernier regions)        Two mAPG variants were generated during this humanization        campaign, which were named APGv2 and APGv4. These variants were        expressed and characterized in several in vitro assays as        described below.

Example 14: Affinity Kinetics for APG Antibodies by Surface PlasmonResonance

Affinity to human glycosylated PAI-1 (GLYHPAI-A, Molecular Innovation)was investigated by Surface Plasmon Resonance (SPR) for mouse APG andthe two humanized variants (APGv2 & APGv4) using a Biacore 2000instrument (GE Healthcare, Uppsala, Sweden).

First, the surface of a Sensor Chip CM5 (GE Healthcare, Uppsala, Sweden)was prepared using routine amine coupling for the capture of the mouseand human anti-Fc (Anti-human IgG (Fc) antibody & Anti-mouse IgGantibody kits, GE Healthcare). All monoclonal antibodies (mAbs) werediluted to 5 nM using HBS-EP running buffer. Each purified mAb wascaptured for three minutes on a different flow cell surface. Human PAI-1was injected at various concentrations (2.5, 5, 10, 20 and 40 nM) withshort dissociation times in between and a long dissociation time at theend (contact time: 120 seconds, short dissociation: 90 seconds; longdissociation: 1800 seconds, flow rate: 50 μl/min). The chip wasregenerated by glycine-HC, pH 1.7 buffer after each round ofantibody-PAI-1 binding. Kinetics data analysis was performed usingBiacore BIAevaluation software. The sensorgrams were double-referencedby subtracting the reference flow cell values and the blank buffervalues. The sensorgrams were fitted by using the simulated kinetics 1:1(Langmuir) model with local Rmax. (see FIG. 19). The data for the threeAPG antibodies are shown in Table 31.

TABLE 31 Binding Kinetics by Biacore Reverse Assay human PAI-1Dissociation Rate Antibody ka (M⁻¹s⁻¹) kd (1/s) Affinity KD (M) APG3.82E+06 4.32E−04 1.131E−10 APGv2 6.58E+06 2.69E−04 4.080E−11 APGv49.48E+06 3.59E−04 3.800E−11

Example 15: Characterization of APG Antibodies in Human Plasma

The mouse APG and the humanized variants APGv2 and APGv4 were screenedfor their ability to block PAI-1 according to the functional assaysdisclosed herein (see, e.g., Examples 6 and 9, above). Briefly, PAI-1activity was evaluated by the ability of this serpin to form stablecomplex with urokinase immobilized on 96 well plates. After washingunbound PAI-1, uPA-PAI-1 complexes were detected by the use ofpolyclonal antiPAI-1 antibodies. The bound polyclonal anti-PAI-1antibodies (which is proportional to active PAI-1 in the sample) wasthen detected using a horseradish peroxidase conjugated secondaryantibody according to manufacturer instructions (Molecular Innovation,Cat # HPAIKT).

Various concentrations of APG humanized variants (APGv2, APGv4) orparental mouse APG antibodies were incubated for 15 min at roomtemperature with undiluted human plasma having a high active PAI-1level. Remaining active PAI-1 level was determined using uPA-PAI-1complex detection by ELISA as described above (see, e.g., Example 6) andaccording to the manufacturer instruction.

Inhibition of PAI-1 activity was calculated for each mAb concentration.Percent inhibition of PAI-1 activity was plotted as a function ofconcentration of APG humanized variants (APGv2, APGv4) or parental mouseAPG antibody. Biostat speed software was used to determine IC₅₀ andI_(max) after three independent experiments (in duplicate)(see FIG. 20).Data is presented below in Table 32.

TABLE 32 Plasminogen Generation in Human Plasma Antibody IC_(50abs) mean± sem (nM) I_(max) mean (%) mAPG 1.81 89.7 APGv2 9.62E−1 94.5 APGv4 1.2894.4

Example 16: Clot Lysis Assay in Human Plasma: A44V11, mAPG, and APGVariant Activity

The fibrinolytic system is often altered in patients with stroke. A clotlysis assay can be used to determine fibrinolytic activity by measuringthe degree of fibrin breakdown. See generally Lindgren, A. et al. Stroke27:1066-1071 (1996). Clot lysis assays have been described in detailelsewhere. See, e.g., Beebe, et al. Thromb. Res. 47:123-8 (1987): Tilleyet al., J. Vis. Exp. 67:e3822.

The functional activity of A44V11 and other PAI-1 neutralizingantibodies was determined using a human plasma clot lysis assay.Briefly, the assay applied here induces clot formation using a mixtureof Tissue Factor/Ca2+ in the presence of tPA and a concentration ofPAI-1 known to inhibit clot lysis. Fibrin polymerization induces anincrease of turbidimetry that was detected by absorbance measurement at340 nm. The ability of the antibody to restore clot lysis was determinedby incubating increasing doses of antibody with normal human plateletpoor plasma.

Briefly, clot lysis experiments were performed in microtiter plates.Citrated human plasma (Biopredic International, Rennes, France) wasincubated with anti-PAI-1 antibody or isotype controle IgG diluted inassay buffer (NaCl, Tris-HCl pH=7.4). After 15 min incubation at roomtemperature, human glycosylated PAI-1 (GLYHPAI-A, Molecular Innovation)was added to a final concentration of 3 nM and incubated for anadditional 10 min. t-PA (sctPA, Molecular Innovation) was then added toa final concentration of 1 nM. Clot formation was induced by anactivation mix comprising Tissue Factor (Innovin®, Siemens HealthcareDiagnostics, Marburg, Germany) diluted to a final concentration of 7.5mM in calcium assay buffer (CaCl₂).

Kinetic reading of absorbance at 340 nm was performed every 30 sec for 5hours with an iEMS microplate reader (ThermoFischer) or aSpectrostarNano (BMG Labtech). To quantify the effect on clot lysis, thearea under curve (AUC) which reflects the balance between clot formationand clot lysis was calculated using GraphPad Prism Software. Therestoration of clot lysis after antibody treatment was determinedaccording to the following calculation:

${Restoration} = {100 \times \frac{{AUC}_{\max \mspace{11mu} {lysis}} - {AUC}_{treated}}{{AUC}_{{no}\mspace{11mu} {lysis}} - {AUC}_{\max \mspace{11mu} {lysis}}}}$

IC₅₀ and I_(max) were calculated using Biostat speed software.

The 1 nM concentration oft-PA yielded complete lysis of normal plasmawithin 2 hours. The 3 nM-concentration of PAI-1 inhibited t-PA-inducedclot lysis. Addition of either t-PA or PAI-1 alone did not affect clotformation. Addition of neither t-PA or PAI-1 did not affect clotformation.

The A44V11 anti-PAI-1 antibody restored human platelet poor plasma clotlysis (see FIG. 21), while the isotype IgG1 did not (see FIG. 22).A44V11 exhibited an IC₅₀ of 2 nM with an I_(max) of 103% at 100 nM (seeFIG. 23).

The humanized variants of APG anti-PAI-1 antibody also restored humanplatelet poor plasma clot lysis (see FIG. 24). APGv2 exhibited an IC₅₀of 2.1 nM and an I_(max) of 114% at 100 nM. APGv4 exhibited an IC₅₀ of2.8 nM and an I_(max) of 116% at 100 nM (see FIG. 25). The clot lysisdata is summarized below in Table 33.

TABLE 33 Inhibition of clot lysis by anti-PAI-1 antibodies Antibody IC₅₀(nM) Imax @ 100 nM A44V11 1.38 113% APG V2 2.08 114% APG V4 2.82 116%mAPG 2.34 123%

Example 17: Assessment of A44V11 Neutralization of PAI-1 in PrimaryHuman Lung Cells

The effect of antibody A44V11 on neutralization of PAI-1 wasinvestigated in a lung cell-based system. TGFβ is considered to be themost potent and ubiquitous profibrogenic cytokine. TGFβ has been shownto induce PAI-1 expression and inhibit the activities of t-PA andplasmin as well as collagen degradation in cultured murine embryofibroblasts (NIH3T3 cells). See Liu, R-M. Antioxid Redox Signal. 10(2):303-319 (2008). Primary lung fibroblasts strains LL29 (CCL-134) andLL97A (CCL-191) from ATCC (Manassas, Va.) were plated overnight in a12-well plate at a concentration of 200,000 cells per well. Cells wereincubated for 48 hours with A44V11 antibody or isotype control (IgG) andTGFβ (R&D Systems, Minneapolis. Minn., cat. #100-B-001) at aconcentration of 5 ng/ml. After 48 hours, cell supernatants wereharvested and analyzed by Western Blot for detection of PAI-1 forms witha rabbit pAb anti PAI-1 (abeam, ab66705).

Cells treated with A44V11 antibody after TGFβ stimulation display PAI-1band as a doublet, which corresponds to the cleaved form of PAI-1 (seeFIG. 26, lane 5). Cells treated with control IgG do not show thisdoublet formation (see FIG. 26, lane 6). This study demonstrates thattreatment of primary human lung cells with A44V11 induces endogenousPAI-1 substrate conformation, which allows PAI-1 to be cleaved byprotease.

Example 18: A44V11 Increases Activation of MMPs

Plasnmin can activate MMPs, enzymes that can degrade most ECM proteinsincluding collagen, the major proteinaceous component of fibrotictissue. In this regard, plasmin is often cited as a general activator ofMMPs. (See Loskutoff, et al. J. Clin. Invest. 106(12):1441-43 (2000)).PAI-1 decreases MMP activation and matrix degradation by blockingplasmin generation, followed by inhibition of fibroblast apoptosis. Theability of A44v11 to stimulate activation of MMPs was investigated in alung cell-based system. Primary lung fibroblasts LL29 (CCL-134) and LL97Å (CCL-191) from ATCC (Manassas, Va.) were plated overnight in a 12-wellplate at a concentration of 250,000 cells per well. Cells were incubatedfor 48 hours with A44V11 or isotype control (IgG) and Lys-Plasminogen(Molecular Innovation, cat. # HGPG-712) at a concentration of 0.1 μM.After 48 hours, cell supernatants were harvested and the activities of avariety of MMPs (including, for example, MMP-1, 2, 3, 7, 8, 9, 12, 13,and 14) were detected using a Sensolyte 520 Generic MMP Assay kit(AnaSpec, Fremont, Calif., cat. #71158) according to the manufacturer'sinstructions.

As shown in FIG. 27, A44V11 stimulates the activation ofplasmin-dependent MMPs in human lung fibroblasts. The chart shows tworepresentative separate experiments. Cells treated with A44V11 andplasminogen showed substantially increased activation when compared tocells treated with an negative IgG1 antibody. This study demonstratesthat A44V11 stimulates MMPs activation in a plasmin-mediated phenomenon.

Example 19: Analysis of A44V11Potency in Lung Fibrosis Mouse Model(Bleomycin Challenge)

Experimental lung fibrosis induced by bleomycin is a well-studied modelof fibrogenesis supported by ample literature. This model of pulmonaryfibrosis resembles that seen in humans and has been used to assess theeffects of potential therapeutic agents as well as basic research. (see,e.g., Molina-Molina et al. Thorax 61:604410 (2006)).

Pharmacodynamics Study in Bleomycin Treated Mice (Fibrosis Model)

Transgenic mice that express human PAI-1 (humanized PAI-1 transgenicmice) were generated by replacing the mouse PAI-1 (SERPINE1) gene CDS(exons and introns)(NCBI Ref. No. NM_008871) with the correspondinghuman wild type PAI-1 gene CDS (NCBI Ref. No. NM_000602.3;NC_000007.13)(see Klinger, K. W. et al. Proc. Natl. Acad. Sci. USA84:8548 (1987)) under the control of the endogenous mouse PAI-1 generegulatory sequences in C57BL/6×129 mice (The Jackson Laboratory, BarHarbor, Me.). Molecular cloning and generation of transgenic mice areperformed according to conventional techniques and according tomanufacturer and breeder instructions. Expression of human PAI-1 andnon-expression of mouse PAI-1 was confirmed in homozygous mice. BothmRNA and protein levels were confirmed by standard qPCR and by ELISA,respectively. Female homozygous humanized PAI-1 transgenic mice aged 8-9weeks and weighing 22-25 g were used for these procedures. Rodent foodand water were provided ad libitum.

Mice received 50 μl of Bleomycin®, (Sanofi, France) dissolved in 0.9%NaCl by intra-tracheal injection via microspayer at a dose of 2 mg/kg.Control mice received 50 μl of 0.9% NaCl. For these procedures, micewere anesthetized with isoflurane (TEM, Lormont, France) by inhalationand then intubated with a 18G cannula. The cannula was connected to aventilator fed with an oxygen/isoflurane mixture to maintain theanaesthesia. Following anesthetization, the microsprayer was introducedin the cannula for bleomycin injection directly into the lungs. Micewere then extubated and allowed to recover from anaesthesia. At day 4,after randomization in 3 groups, mice were treated once byintra-peritoneal administration of either A44v11 or negative controlmouse IgG1 at 10 mg/kg in PBS (1 mg/ml).

At designated time points (day 7 or day 9) after bleomycin challenge,mice were anesthetized with a xylazine/ketamine mix and euthanized bychest opening. A blood collection was performed by intra-cardiac harveston a citrate coated tube. Left bronchia was clamped and the left lungwas removed and fixed with a fixator (FineFix®, Leica Biosystems.Buffalo Grove, Ill.) under controlled pressure for histological analysisA cannula was then placed into the trachea for the broncho-alveolarlavage (BAL) procedure (1.5 ml of 0.9% NaCl injected and harvest inthree injections of 0.5 ml). The four lobes of the right lung were thenharvested, cut in two pieces and lysed for protein analysis. Allexperiments were performed in accordance with European ethical lows andapproved by internal ethical comity (CEPAL, sanofi).

A44V11 levels were determined using ELISA (Molecular Innovation, cat. #HPAIKT) with coated biotinylated human PAI-1 plates and detected usingsecondary anti mouse IgG sulfo-tag labeled (MesoScale Discovery,Gaithersburg, Md.). For Day 7 mice treated with A44V11, the result was200 nM in plasma, 11 nM in BALF and 12 nM in lung lysate.

As shown in FIG. 28, administration of a single intra-peritoneal dose(10 mg/kg) of A44V11 at day 4 achieves nearly full inhibition of humanactive PAI-1 both in BAL fluid and in lung lysate in animals sacrificedat day 7 alter bleomycin challenge. For day 9 animals. A44V11 (10 mg/kg)achieves nearly full inhibition of human active PAI-1 in lung lysates,but achieves only partial inhibition in BALF.

D-dimers, a fibrin degradation product, can be measured to assess thedegree of fibrin breakdown. To measure fibrin degradation, the levels ofD-dimer in BALF were detected by ELISA (Asserachrom D-Di, DiagnosticaStago. Asnieres, France) according to manufacturer instructions. D-dimerlevels in the BALF of the A44V11-treated group were increasedapproximately 2.8-fold at day 7 and 1.6-fold at day 9 when compared tothe IgG1 negative control group, suggesting A44V11 treatment increasesfibrin degradation (see FIG. 29).

Additional studies were performed to further assess A44V11 activity inreducing fibrosis in mouse lung challenged with bleomycin. For thesestudies, mice were subjected to a similar protocol to the pharmacodynamystudy described above, except that the study duration length was 21 daysfrom bleomycin challenge, and treatment with antibody (either A44V11 orIgG1 control antibody at 10 mg/kg) was repeated every 3 days starting atday 4 until day 20. At day 21 after bleomycin challenge, the animalswere sacrificed as described above.

Increase in lung weight is known to be an indicator of increasedfibrosis. The right lung weight, as a measure of fibrosis, wasdetermined for mice in all experimental groups. As shown in FIG. 30,bleomycin instillation induces an increase in right lung weight that waspartially inhibited by repeated dosing of A44V11 antibody at 10 mg/kg.Repeated dosing using the IgG1 negative control antibody did not inhibitthe increase in right lung weight due to bleomycin challenge. Thereduction in bleomycin-induced right lung weight increase inA44V11-treated mice was statistically significant when compared tosimilar bleomycin-induced mice that were treated with IgG1 negativecontrol antibody (p<0.001). Statistical analysis was performed byone-way ANOVA followed by Newman-Keuls test. This result indicates thatA44V11 inhibits bleomycin-induced fibrosis in the humanized PAI-1 mouselung, whereas a control IgG1 antibody does not.

Collagen accumulation in the lung is another known indicator offibrosis. To assay collagen accumulation, lung tissues from micesacrificed at day 21 were prepared and separated by HPLC, followed bythe measurement of hydroxyproline. This technique is detailed elsewhere,for example in Hattori, et al. J. Clin Invest. 106(11):1341-1350 (2000).In brief, lung tissue was prepared by hydrolysis under acidic condition(6M HCl) for 22 hours at 105° C., followed by evaporation. Primaryamines were blocked in the lung tissue by OPA (phthalaldehyde), andproline/hydroxyprolines were specifically labeled using NBD(4-chloro-7-nitrobenzofurazan) (Santa Cruz Biotech., Santa Cruz,Calif.). Hydrolysates were then separated on Synergi™ 4 μm Hydro-RP 80Å, LC Column 150×3 mm columns (Phenomenex, Torrance, Calif., cat.#00F-4375-Y0) using HPLC (Shimazu Corp., Kyoto, Japan) underacetonitrile gradient. Standard curves of known amounts ofhydroxyproline were used as reference to quantify peak(s). Arepresentation of the quantified data are shown in FIG. 31.

Lung collagen accumulation as detected by hydroxyproline content wasincreased in bleomycin challenged animals. This increase in lungcollagen accumulation was statistically reduced (p<0.08) by repeateddosing of A44V11 antibody at 10 mg/kg. (see FIG. 31). Repeated dosingusing the IgG1 negative control antibody did not inhibit the increase inlung collagen accumulation due to bleomycin challenge. The reduction inbleomycin-induced collagen accumulation increase in A44V11-treated micewas statistically significant when compared to similar bleomycin-inducedmice that were treated with IgG1 negative control antibody (p<0.05).A44V11-treated mice showed approximately 44% less of an increase incollagen accumulation than IgG1 control-treated mice.

Example 20: Assessment of A44V11 Activity in LPS Challenge Model inMonkeys

An acute lipopolysaccharide (LPS) challenge model in monkeys was appliedto determine the PAI-1 neutralization efficacy of A44V11 in vivo. TheLPS challenge model is described in Hattori, et al J. Clin Invest.106(11): 1341-1350 (2000). The activity of A44V11 mAb on PAI-1 in monkeyplasma and liver samples was evaluated. Specifically, the experiment wasdesigned to assess the impact of a high dose of LPS (100 Mg/kg-IV) onplasma and tissue levels of PAI-1 in the anesthetized monkey pre-treated(24 hours before) either with A44V11 (5 ng/kg, IP) or IgG1 (negativecontrol, 5 mg/kg, intra peritoneal administration). Experiments wereperformed in accordance with European ethical lows and approved byinternal ethical comity (CEPAL, sanofi).

Cynomolgous Macaca fascicularis (male and female) weighing 4 to 9 kgwere food-deprived overnight before long-term anesthesia (at least 8hours), including IM induction with Zoletil 50 (Virbac, Taguig City,Philippines) at 0.12 to 0.16 mL/kg followed by inhalation of a gaseousmix of air/oxygen and isoflurane (1 to 3%). Monkey body temperature wasmaintained within physiological ranges using a heating pad. Aftercatheterization, LPS (Serotype 0127-B8) was administered as a 1 minbolus in the cephalic accessory vein at a dose of 100 μg/kg (0.4 mL/kg).At various time points, blood samples and liver samples were taken.Blood samples (on citrate/EDTA) were harvested and centrifuged toisolate platelet poor plasma. Liver biopsies and terminal necropsy werestored at −80° C.

Active PAI-1, D-dimer and plasmin-α2 antiplasmin levels were determinedusing commercially available ELISA assays (Mol. Innovation, cat. #HPAIKT; Asserachrom D-Dimer; Plasmin-A2 antiplasmin, Diagnostica Stago)according to manufacturer instructions.

In plasma, active PAI-1 level decreases from about 30 ng/ml to below 10ng/ml in all monkeys administered with A44v11. (See FIG. 32(A)). Therewas no increase in active PAI-1 levels after LPS administration (100ug/kg). (See FIG. 32(A). In contrast, monkeys treated with negative IgG1control show a strong increase in active PAI-1 levels following LPSadministration, with a maximum occurring at about 4 hr (approximately 50to about 250 ng/ml). (See FIG. 32(B)). Thus, treatment with negativeIgG1 control does not reduce the active PAI-1 levels in plasma that werestrongly increased after LPS administration. (See FIG. 32(B)).

In liver biopsy lysates, a similar phenomenon was observed. Monkeys thatwere treated with A44V11 mAb did not show an increase in active PAI-1levels following LPS treatment. (See FIG. 33(A)). In contrast, LPSadministration induced a strong increase of active PAI-1 (up to 3 ng/mg)in liver biopsy lysates from negative IgG1 control-treated monkeys (seeFIG. 33(B)).

Simultaneously to PAI-1 neutralization, the D-dimer levels inA44V11-treated monkeys (see FIG. 34(A)) was found to generally be higherthan negative IgG control-treated monkeys (see FIG. 34(B)) thussuggesting that A44V11 treatment in monkeys also induces an increase offibrin degradation in plasma.

Finally, plasma samples of A44V11-treated monkeys showed an increasedlevel of plasmin-α2 antiplasmin (PAP) complexes when compared to the PAPlevels in negative IgG control-treated monkeys. (see FIGS. 35(A) and(B)). The increase in PAP complex and D-dimer in the presence of A44V11indicates increases in plasmin generation.

Example 21: Assessment of A44V11 Activity in Abdominal Adhesion MouseModel

The effect of treatment with anti-PAI-1 antibody A44V11 on the formationof adhesions was evaluated in a mouse uterine horn model of surgicalinjury. The mouse uterine horn approximation and electrocauteryprocedure disrupts the serosal surface, causes thermal damage to theuterine tissue, and approximates damaged tissue surfaces during thehealing process that ultimately results in post-surgical adhesions in100% of untreated animals. The model and surgical procedure has beenpreviously described in Haney A. F. et al., (1993). Fertility andSterility. 60(3): 550-558.

For these adhesion studies, the transgenic female mice generated abovethat express humanized PAI-1 transgene, approximately 9 weeks old,weighing approximately 20 g, were used. Forty-two mature transgenicfemale mice were divided into two groups and subjected to the surgicalprocedure designed to create adhesions between the uterine horns (UH),as described in detail in Haney A. F. et al., (1993). Briefly, eachanimal was anesthetized with isoflurane for the surgery according toTACUC guidelines, and a routine midline laparotomy was performedapproximately 1.0 cm caudal to the xyphoid process. The UH wereidentified, approximated medially with a single 7-0 Prolene suture(Ethicon Inc., Somerville, N.J.) carefully placed through the musclewall of each horn, and the horns tied together immediately below thejunction of the oviducts at the uterotubal junction. Care was taken notto damage the ovarian vascular supply. To induce electrocautery injury,a bipolar electro cautery unit was used (Valley Lab Surgistat, Solidstate Electrosurgery Unit, Model No. B-20) on the medial surfaces ofeach uterine horn, covering an area of approximately 2×6 mm. The cauteryunit was set as follows: Volts 100, 130 Hz, 50-60 Amps. A 3 mm widecautery tip was used with pure coagulating current at a setting of 3,power was initiated, and the tissue touched for 1 second at two burnspots per horn. The muscle incision was closed with 5-0 Vicryl, BV-1taper needle (Ethicon Inc.) in a continuous suture pattern. Skin wasclosed with 5-0 Prolene, BV-1 Taper needle (Ethicon Inc.), in ahorizontal mattress suture pattern.

Following the creation of the UH injury, Group 1 animals were treatedwith a volume of 0.16 mL of an Isotype Control antibody (30 mg/kg),which was applied to the cautery burns. Group 2 animals were treatedwith a volume of 0.16 mL of A44V11 antibody (30 mg/kg) in the samemanner. For each group, animals were euthanized at 6 hours (n=5), 72hours (n=4), or at Day 7 (n=12). (See Table 34 below). Animals that werescheduled for euthanasia at 72 hours and Day 7 had second dose ofantibody (30 mg/kg) injected intraperitoneally (IP) 48 hours aftersurgery.

TABLE 34 Treatment schedule for uterine horn injury studies. Time point# of Dosing Group Treatment Euthanized Animals (30 mg/kg) Group 1Isotype Control 6 hours 5 Time 0 mAb (0.16 mL) 72 hours 4 Time 0 + 48hours Day 7 12 Time 0 + 48 hours Group 2 Anti-PAI-1 A44 6 hours 5 Time 0humanized mAb 72 hours 4 Time 0 + (0.16 mL) 48 hours Day 7 12 Time 0 +48 hours Note: All animals had uterine horn approximated by suture andcautery burns created prior to treatment.

Efficacy Evaluation and Analysis:

Animals were euthanized at the indicated time points and the formationof adhesions was evaluated. Briefly, the length of the horns wasmeasured from the uterine bifurcation to the approximation suture placedjust below the oviducts. The two external sutures surrounding theuterine horns were removed and the length of adhesion between uterinehorns was measured with the aid of a microscope, documented, and notedas present or absent (Yes/No). Also, any tissues involved in theadhesion formation will be recorded but may not be included in thelength of adhesed area. The distribution of the average percent ofadhesed length between uterine horns was checked for normality using theShapiro-Wilk Test. The groups were compared with each other using TukeyKramer analysis if normally distributed and Wilcoxon Rank-Sum analysisif not normally distributed. In all cases, a p-value ≤0.05 wasconsidered statistically significant. Animals treated with A44V11 showedsignificantly lower percent of length of adhesion formation betweenapproximated uterine horns (see

TABLE 35 Uterine Horn length measurement results. % of Length withAdhesions between the Uterine Horns Group N (Mean ± SEM) Isotype ControlmAb 12 84 ± 3  (0.16 mL) A44V11 mAb 11 61 ± 7* (0.16 mL) (p = 0.02) *p =statistically significant relative to the Isotype Control by WilcoxonRank Sum Analysis, Chi Square Approximation

Detection of Active PAI-1 and tPA Levels

Following euthanasia, animals had blood (plasma), intraperitoneal fluid(IPF), and uterine horn samples collected for evaluation. Collection ofsamples were performed using conventional techniques. Plasma, IPF, anduterine horn samples were evaluated for active PAI-1 and tPA levelsusing ELISA. (Human PAI-1 Activity ELISA kits, Cat. # HPAIKT, MolecularInnovations, Novi, Mich.). Data was processed using Excel, JMP, andPrism Graph pad software. In all cases, a p-value ≤0.05 was consideredstatistically significant. At 6 hour and Day 7 time point, decreasedlevels of active PAI-1 were found in the IP Fluid and Uterine HornLysates in the animals treated with A44V11 versus Isotype Control. (SeeFIG. 36). The decreased levels of active PAI-1 in the IPF at 6 hours wasstatistically significant result shown in IP Fluid at 6 hour time pointin animals treated with A44 versus to Isotype Control (p<0.001 byStudent T-test).

Example 22: Crystal Structure of Humanized Antibody A44V11 Expressionand Purification of Fab A44V1

Recombinant Fab (rFab) was obtained from transiently transfected HEK293cells, using two plasmids encoding the light chain or the C-terminalHis-tagged heavy chain. After centrifugation and filtering, rFab fromthe cell supernatant was applied to an immobilized-metal affinity resin.After elution from the resin, the rFab was extensively dialyzed againstPBS & stored at 4° C.

Source of Macaca Fascicularis PAI-1, Referred as Cynomolgous or CynoPAI-1:

Recombinant mature cynomolgous PAI-1 (24-402) was expressed as inclusionbodies in E. coli and the recombinant protein was purified usingconventional methods.

Source of Human PAI-1:

Recombinant mature human PAI-1 (24-402) was purchased from MolecularInnovations Inc. (catalogue number CPAI). It was a stabilized in activeconformation by introducing mutations (N150H, K154T, Q319L, M354I), asdescribed by Berkenpas et al. (1995, EMBO J., 14, 2969-2977).

Preparation & Purification of the Complexes:

Recombinant Fab & antigen were mixed at a 1.5:1 molar ratio, incubated30 min at room temperature, and the complexes were further purified bypreparative size exclusion on a Superdex 200 PG column (GE Healthcare),equilibrated with 25 mM MES pH 6.5, 150 mM NaCl.

Crystallization of the Fab A44V111+Cyno PAI-1 Complex

The complex was concentrated to 10 mg/ml in 25 mM MES pH 6.5, 150 mMNaCl. It crystallizes in 16-24% ethanol, 100 mM Tris pH 8.5. Ethyleneglycol (30%) was used as cryoprotectant. Crystals diffracted to about3.3 Å in space group P321 (a=b=193 Å, c=144 Å) on ID29 beamline of ESRF.Data was processed with a combination of XDS and Scala (GlobalPhasingLtd., Cambridge. UK)

Structure Determination of the Complex Fab A44V11/Cyno-PAI-1:

A model of the Fab variable domain was constructed using Prime inMaestro (Schrodinger, New York, N.Y.). The constant domain was obtainedfrom published structure 3FO2. Two different models of human PAI-1 wereused: the latent conformation was obtained from 1LJ5, the activeconformation from 1OC0. Calculation of Matthews Coefficient (V_(M),crystal volume per unit of protein molecular weight) suggests that thereare up to four complexes in the asymmetric unit (V_(M)2. 2 assuming acomplex size of 90 kilodaltons (KD). Molecular Replacement was doneusing Phaser (CCP4 suite)(McCoy, et al. J. App. Cryst. 40: 658-674(2007), which identified two monomers of latent PAI-1 and two variabledomains of Fab. Additional density was clearly visible for the constantdomains, which had to be placed manually. This solution, whichcorresponds to a V_(M) of 4.3 (71% solvent), was also carefully examinedfor packing consistency. The structure was refined with Buster(GlobalPhasing) using non crystallographic symmetry, to an Rfree of29.2% (Rfactor 25.8%). The constant domains are not stabilized bycrystal packing and are poorly resolved in the electron density map.

Crystallization of the Fab A44V11+Human PAI-1 Complex

Protein crystallization is a bottleneck of biomolecular structuredetermination by x-ray crystallography methods. Success in proteincrystallization is directly proportional to the quality of the proteinmolecules used in the crystallization experiments, where the mostimportant quality criteria are purity and homogeneity (both molecularand conformational) of the proteins in solution.

Initially, to determine the PAI-1/Fab mAb complex structure a native mAbA44 was used to prepare its Fab fragment by papain digestion. This Fabscaled up preparation resulted heterogeneous Fab fragments which werecomplexed and purified in complex with human wild type (wt) PAI-1protein. The obtained protein complex was concentrated to 7 mg/mlconcentration and screened for crystallization under 800 individualcrystallization conditions at two different temperatures, 4° C. and 19°C. No crystallization hits were detected. In order to improve theprotein complex homogeneity recombinant 6-His tagged Fab A44 wasproduced, purified and complexed with the human wild type PAI-1 protein(see FIG. 36).

The complex crystallization screening resulted first crystallizationhits under 20% PEG10K+0.1 M Sodium Acetate pH4.6 conditions.Crystallization optimization by conventional crystallization methods,Microseed Matrix Seeding, and in situ Trypsinolysis crystallization didnot significantly improve the quality of crystals. The best obtainedcrystals were needle-like and were diffracting x-rays with insufficientresolution for structure determination (10 Å).

The failure with the complex crystals crystallization could potentiallybe explained by the complex conformational heterogeneity. The wild typePAI-1 molecule is known to adopt three distinct conformations (active,latent, and substrate) which may interfere with crystallization. Toimprove the quality of the crystals, 6-His tagged A44 Fab in complexwith latent PAI-1 was produced. (see FIG. 37).

The corresponding complex was produced and screened for crystallizationdo novo and under conditions previously used for 6-His tagged Fab A44/wtPAI-1 protein complex. The only crystallization hit out of the more than1000 conditions tested was identified for the complex under 20%PEG3350+0.2M nH4 Acetate+4% MPD+50 mM Mcs pH6 conditions (see FIG.39(a)). After extensive optimization 3D crystals were obtained. X-Raydiffraction tests using synchrotron high intensity X-Ray beam showed nodiffraction sign (see FIG. 39(b), depicting representative optimizedcrystals).

To reduce the flexibility of portions of the protein it was decided toproduce A44 Fab fragment recombinantly but without an artificial tagsuch as the 6-His tag used previously. To further increase the chancesfor successful crystallization, an active form mutant of PAI-1 (N150H,K154T, Q319L, M354I) was purchased from Molecular Innovations (Cat.#CPAI, Novi, Mich.) and used for complex preparation with Fab A44protein lacking artificial tag. The complex was concentrated to 12 mg/mlin 25 mM MES pH 6.5, 150 mM NaCl. Acceptable rod-like single crystalswere obtained in 10% PEG3350, 100 mM ammonium sulfate and cryoprotectedby the addition of 30% ethylene glycol (see FIG. 40). These crystalsdiffracted to 3.7 Å resolution, and after extensive cryoprotectionoptimization, resulted in an x-ray diffraction data set suitable for thestructure determination (3.3 Å). A dataset was collected to 3.3 Å atbeamline Proxima 1 of synchrotron SOLEIL (Saint-Aubin, France).Spacegroup is P212121 (a=105, b=152 c=298). Data was processed usingXDSme scripts (XDS ref. Xdsme ref).

Structure determination of the complex Fab A44V11/Human-PAI-1:

Pointless (CCP4) indicated only a 40% confidence in spacegroupidentification. In consequence, initial Molecular Replacement was earnedout with Amore (CCP4) to test all possible space group variants of theP222 point group: P212121 was unambiguously confirmed. Final MolecularReplacement with Phaser (Phaser, CCP4) identified four dimers of activePAI-1/variable domain of Fab in the asymmetric unit. The constantdomains were added manually in the electron density map. The structurewas refined with Buster (GlobalPhasing) using non crystallographicsymmetry, to a Rfree of 28% (Rfactor 24.1%).

Epitope and Paratope Structural Analysis

Epitope and paratope regions were identified as formed in the cyno andhuman complexes, and the complexes were compared. The crystal structureswere determined to 3.3 Å for A44V11 in complex with human and cynoPAI-1. The superimposition of both structures (see FIG. 40) shows thatthe paratope of A44V11 is similar for both latent and active forms ofPAI-1. Fab A44 recognized the active form of human PAI-1 and the latentform of cyno PAI-1. FIG. 42 depicts the PAI-1 epitope recognized by FabA44 in both active human PAI-1 (FIG. 42(A)), and latent cyno PAI-1 (FIG.42(B)). The paratope-recognizing the latent conformation is part of theparatope recognizing the active conformation.

PAI-1 interacts mostly with the heavy chain of A44V11, as can be seenfrom the analysis of the surface areas of interaction. Surface area ofthe interaction between active human PAI-1 and the heavy chain (averageof 4 complexes) is 674 Å². Surface area of the interaction betweenactive human PAI-1 and the light chain (average of 4 complexes) is 372Å². Surface area of the interaction between latent cyno PAI-1 and theheavy chain (average of 2 complexes) is 703 Å². Surface area of theinteraction between latent cyno PAI-1 and the light chain (average of 2complexes) is 360 Å². See FIGS. 43 and 44 for depictions of theparatopes of the heavy chain and light chain, respectively.

The residues of the A44V11 part of the paratope are shown below in Table36. Residues in italic are involved in the interactions with activePAI-1 but not the latent form, while residues underlined are interactingonly with the latent form. All other residues are involved in bothinterfaces.

TABLE 36 A44V11 residues involved in paratope with PAI-1 LocationResidues Heavy Chain (FIG. 43) Loop H1 Thr30, Asn31, Gly32, Tyr33 andAsn35 Loop H2 and neighboring Tyr47, Tyr50, Thr52, Tyr53, Ser54,β-strands Gly55, Ser56, Thr57 and Tyr58 Loop H3 Trp98, Tyr100 and Tyr104Light Chain (FIG. 44) Loop L1: Asn30 and Tyr32 Loop L2: Arg50 and Arg53Loop L3: Tyr91, Asp92, Glu93, Phe94 and Pro96

Despite the different conformations of the human and cyno PAI-1molecules, the same residues are involved in interactions with the FabA44 (bolded residues shown below in the sequence of human PAI-1) (SEQ IDNO: 1):

VHHPPSYVAHLASDFGVRVFQQVAQASKDRNVVFSPYGVASVLAMLQLTTGGETQQQIQAAMGFKIDDKGMAPALRHLYKELMGPWNKDEISTTDAIFVQRDLKLVQGFMPHFFRLFRSTVKQVDFSEVERARFIINDWVKTHTKGMISHLLGTGAVDQLTRLVLVNALFNGQWKTPFPDSSTHRRLFHKSDGSTVSVPMMAQTNKFNYTEFTTPDGHYYDILELPYHGDTLSMFIAAPYEKEVPLSALTNILSAQLISHWKGNMTRLPRLLVLPKFSLETEVDLRKPLENLGMTDMFRQFQADFTSLSDQEPLHVALALQKVKIEVNESGTVASSSTAVIVSARMAPEEIIIDRPFLFVVRHNPTGTVLFMGQVMEPShort-hand for the A44V11 binding epitope for human PAI-1 is as follows:

(SEQ ID NO: 156) E-X-X-Q; (SEQ ID NO: 157) L-X-R; (SEQ ID NO: 158)T-D-X-X-R-Q-F-Q-A-D-F-T-X-X-S-D-Q-E-P-L 

In summary, the cyno and human epitopes of PAI-1 recognizing FabA44 areidentical in both conformations. Fab A44 recognizes both human and cynoPAI-1 but likely not mouse or rat PAI-1.

Example 23: Determination of A44V11 Specificity and Cross-Reactivity

To determine the specificity and reactivity of A44V11, the sequence ofthe A44V11 epitope (see above) was used to search for similar epitopesin other proteins using a motif search with ScanProsite (SIB SwissInstitute of Bioinformatics) database. For additional details seeArtimo, P. et al. Nucleic Acids Res. 40(W1):W597-603 (2012). All of theepitope sequence matches located in the search were related to PAI-1,suggesting that the A44V11 antibody is specific for PAI-1.

The A44V11 epitope was also compared to other known x-ray structures (3Dsearch) using in silico profiling and molecular modeling according toMed-SuMo, which detects and compares the biochemical functions onproteins surfaces, including for example hydrogen bonds, charges,hydrophobic and aromatic groups. Med-SuMo molecular modeling is furtherdescribed in Jambon, et al Bioinformatics 21(20):3929-30 (2005). The 3Dsearch of the A44V11 epitope located a similar motif in humanalpha-1-antitrypsin (AAT1). However, upon further investigation, theA44V11 motif was found to have significant differences between theA44V11 epitope, such that A44V11 is unlikely to bind. Therefore,sequence pattern and 3D pattern analysis of the A44V11 epitope suggeststhat there should be minimal cross-reactivity with other human proteins.

The human and cyno PAI-1 epitopes for A44V11 were compared to proposedepitopes from mouse and rat PAI-1. Sequences are excerpted from SEQ IDNO:1 (PA-1 human), SEQ ID NO:162 (PAI-1 cyno). SEQ ID NO:163 (PAI-1mouse), and SEQ ID NO:164 (PAI-1 rat). Rat and mouse PAI-1 haverespectively 75% and 79% sequence identity with human PAI-1. Alignmentof the different PAI-1 sequences show significant differences betweenrat/mouse and human/cyno sequence in their respective epitopes,suggesting that A44V11 is unlikely to recognize rat or mouse PAI-1 (SeeFIG. 45). For example, mouse PAI-1 amino acids Ser300, Thr302, Gln314are different from the human/cyno PAI-1 counterparts. The differences inthese residues represent a change in proposed epitopes, such that mousePAI-1 cannot be recognized by A44V11. The structural comparison of themouse PAI-1 with the structure of the complex human PAI-1/A44V11 (FIG.46) further indicates that it should not be possible to obtain bothhuman and mouse activity from the A44V11 antibody.

To further validate the identified epitope for A44V11, the human andcyno A44V11 epitopes were compared to binding regions of vibronectin.The structure of human PAI1 in complex with the somatomedin B domain ofvibronectin has been published (1OC0). The structures of these twocomplexes were compared (see FIG. 47). The structural comparisonsuggests that the binding of A44V11 will not impact PAI-1 interactionwith vibronectin.

The A44V11 epitope was compared to the epitopes of other publishedanti-PAI1 antibodies. No overlap of the A44V11 epitopes was found withother published anti-PAI-1 antibodies MA-55F4C2 and MA-33H1, which bindresidues in the 128-156 region (see Debrock et al. Thromb Haemost.79:597-601 (1998)).

Finally, the specificity and lack of cross-reactivity of the A44V11antibody was confirmed by Biacore. Based on the predicted uniquesequence and 3D structure of the A44V11 epitope, molecular modelingstudies indicate strongly that the A44V11 is specific for human and cynoPAI-1.

Example 24: Epitope Mapping by Hydrogen/Deuterium Exchange MassSpectrometry (HDX MS)

Hydrogen/deuterium exchange (HDX) monitored by mass spectrometry (MS)was applied to the PAI-1-binding antibodies disclosed herein to furthercharacterize the epitopes of each antibody. HDX MS is a particularlyuseful technique for comparing multiple states of the same protein.Detailed methodology and applications of HDX MS to protein therapeuticsare disclosed in Wei, et al., Drug Discovery Today, 19(1): 95-102(2014). Briefly, if an aqueous, all-H₂O solvent is replaced with anisotope of hydrogen that has distinctive spectroscopic properties, thenone can follow this exchange process. For most modem HDX experiments,deuterated or “heavy” water (D₂O) is used. In particular, the hydrogenbonded to the backbone nitrogen (also referred to as the backbone amidehydrogen) is useful for probing protein conformation. See, e.g.,Marcsisin, et al. Anal Bioanal Chem. 397(3): 967-972 (2010). The exposedand dynamic regions of proteins will exchange quickly, while protectedand rigid regions of proteins will exchange slower. All of the relevantconditions (pH, temperature, ionic strength, etc.) are kept constant, soonly the difference in structure (solvent accessibility, hydrogenbonding) impacts this exchange. The interaction of the antibody withPAI-1 will block the labeling of certain portions of the antigen, thusproducing a different readout based on the site of binding (epitope).

Experimental Method:

Stock solutions of cyno-PAI-1 (10 uM), cyno-PAI-1 bound to A44v 11 (10μm each) and cyno-PAI-1 bound to APGv2 (10 μm each) were prepared inPBS, pH 7.2. The protein solutions were allowed to reach bindingequilibrium by incubating for 1 hour at room temperature. Based on aK_(d) value of <50 pM, each of the antibody:antigen complexes were >99%bound under the labeling conditions described below.

Deuterium exchange, quenching, and sample injection were handled by anautomated robotics system (LEAP Tech., Carrboro, N.C.). An aliquot ofthe protein solution was diluted 10-fold with labeling buffer (PBS in99.9% D₂O, pD 7.2) and allowed to incubate at 20° C. for 10 see, 1 min,5 min, or 4 hours. At the end of the deuterium exchange time point, thelabeling reaction was quenched by adding 50 μL of the labeling solutionto an equal volume of pre-chilled (0° C.) 100 mM sodium phosphate, 4 Mguanidine hydrochloride, 0.5 M TCEP, pH 2.5. Undeuterated controls wereprepared in an identical fashion by diluting 10-fold with PBS in H₂O.

Each quenched sample (50 μL, 50 pmol of each protein) was immediatelyinjected into a Waters nanoAcquity with HDX Technology (Waters Corp.,Milford, Mass.). The proteins were digested online with a 2.1 mm×30 mmEnzymate BEH pepsin column (Waters Corp.) which was held at 20° C. Allof the chromatographic elements were held at 0.0±0.1° C. inside thecooling chamber of the ultra-performance liquid chromatography (UPLC)system. The resulting peptides were trapped and desalted for 3 min at100 μL/min and then separated on a 1.0×100.0 mm ACQUITY UPLC HSS T3column (Waters Corp.) with a 12 min, 2-40% acetonitrile:water gradientat 40 L/min. Deuterium levels were not corrected for back exchange andwere reported as relative. All comparison experiments were done underidentical conditions, negating the need for back exchange correction.All experiments were performed in triplicate. Peptide carryover betweeninjections was eliminated by injecting 50 μL of 1.5 M guanidinehydrochloride, 0.8% formic acid, and 4% acetonitrile over all columnsafter each run.

Mass spectra were acquired with a Waters Synapt G2-Si instrumentequipped with a standard electrospray source (Waters Corp.) run in HDMSemode. Instrument settings were as follows: capillary was 3.5 kV,sampling cone was 30 V, source offset was 30 V, source temperature was80° C., desolvation temperature was 175° C., cone gas was 50 L/hr,desolvation gas was 600 L/h, and nebulizer gas was 6.5 bar. Mass spectrawere acquired over an m/z range of 50-1700. Mass accuracy was maintainedthrough each run by simultaneous infusion of 100 fmol/uL human[Glu1]-Fibrinopeptide B through the lockmass probe.

MSE identification of the undcuteratcd peptic peptides was preformedusing ProtcinLynx Global Server software (Waters Corp.). Deuteriumuptake for each peptide was determined using DynamX 2.0 software (WatersCorp.). Relative deuterium levels were calculated by subtracting thecentroid of the isotopic distribution for undeuterated peptides from thecorresponding centroid of the deuterium-labeled peptide. Deuteriumuptake plots were generated automatically by the software.

Monitoring Deuterium Uptake for PAI-1 States

After online pepsin digestion, 150 overlapping cyno-PAI-1 pepticpeptides were identified, resulting in 95.3% sequence coverage (see FIG.48). Deuterium uptake was monitored (from 10 sec to 4 hours) in all 150peptides for three different protein states: (1) cyno-PAI-1 alone; (2)A44v11 bound to cyno-PAI-1; and (3) APGv2 bound to cyno-PAI-1.

The majority of the cyno-PAI-1 peptides showed nearly identicaldeuterium uptake between the three states, which indicates that there isno interaction between cyno-PAI-1 and either mAb in these regions. SeeFIG. 49(A), which depicts one representative peptide region with thisresult (residues 139-152). In contrast, peptides incorporating residues44-64 showed significant protection from exchange (reduced deuteriumuptake) when bound to either A44v11 or APGv2 (FIG. 49(B)). In addition,peptides incorporating residues 295-322 also showed significantprotection from exchange when bound to either A44v11 or APGv2 (FIG.49(C)). For this region, the magnitude of protection was greater whencyno-PAI-1 was bound to A44v11 rather than APGv2 (See FIG. 49(C)). Thisindicates that A44v11 may provide greater overall protection fromexchange than APGv2 when bound to cyno-PAI-1.

Comparison Studies:

For comparison studies, deuterium uptake was monitored for all of the150 peptides generated from each of the three cyno-PAI-1 states. (See,generally, Wei, et al., Drug Discovery Today, 19(1): 95-102 (2014)).Data plots from each of the three states were compared to one anotherand a butterfly plot was generated to facilitate data interpretation(see, e.g., FIGS. 50(A), 51(A), and 52(A)). For each butterfly plot, thex-axis is the calculated peptide midpoint position, i, of each of the150 peptides compared; the y-axis is the average relative fractionalexchange (ratio).

Difference plots were also generated for each comparison between thecyno-PAI-1 states (see, e.g., FIGS. 50(B), 51(B), and 52(B)). In theseplots, the deuterium uptake from one state is subtracted from the otherand plotted similarly to the butterfly plots. The sum of the differencesfor each peptide is represented by a vertical bar. The horizontal dashedlines represent the values at which either individual measurements (±0.5Da) or the sum of the differences (±1.1 Da) exceed the error of themeasurement and can be considered as real differences between the twostates. Additional details regarding this technique are disclosed inHoude D. et al., J. Pharm. Sci. 100(6):2071-86 (2011).

First, cyno-PAI-1 alone was compared to the A44v11:cyno-PAI-1 boundstate (FIG. 50). The butterfly plot for this comparison is shown in FIG.50(A). The difference plot for this comparison is shown in FIG. 50(B).The observed differences between cyno-PAI-1 bound to A44v 11 and freeform cyno-PAI-1 are located primarily in two regions of cyno-PAI-1. Oneregion is near the N-terminus (residues 44-64) and the other region isnear the C-terminus (residues 307-321) (see FIG. 50(B)).

Next, cyno-PAI-1 alone was compared to the APGv2:cyno-PAI-1 bound state(FIG. 51). The butterfly plot for this comparison is shown in FIG.51(A). The difference plot for this comparison is shown in FIG. 51(B).The observed differences between cyno-PAI-1 bound to APGv2 and free formcyno-PAI-1 are located primarily in two regions of cyno-PAI-1. Oneregion is near the N-terminus and the other near the C-terminus, whichis similar to the A44v11:cyno-PAI-1 result. The A44v11 and APGv2complexes with cyno-PAI-1 share peptides showing reduced deuteriumuptake when in the bound state, which may indicate that the epitopes forthe two antibodies are similar.

Finally, the two antibody-bound cyno-PAI-1 states were compared to eachother (FIG. 52). The butterfly plot for this comparison is shown in FIG.52(A). The difference plot for this comparison is shown in FIG. 52(B).The observed difference between A44v11:cyno-PAI-1 and APGv2:cyno-PAI-1is located in the C-terminal region of cyno-PAI-1. (See FIG. 52(B)).

Example 25: Epitope Comparison of Antibodies A44v11 and APGv2

HDX MS was used to further define the epitopes of the A44v111 and APGv2antibodies. By using the overlapping peptides generated in HDX MS, anantibody epitope can be refined to slightly better than peptide-levelresolution (for example, see FIG. 48). The HDX MS data for the peptideswhich showed significant protection from exchange with A44V11 bindingwas further analyzed to determine the epitope for the cyno-PAI-1:A44v11interaction. The HDX data for the A44V11 epitope of cyno-PAI-1 was foundto be consistent with the epitope determined using the crystallographyapproach. The A44V11 epitope of cyno-PAI-1 identified using HDX MSappears in FIG. 53 (bold), and below in shorthand format:

(SEQ ID NO: 159) T-T-G-G-E-T-R-Q-Q-I-Q; (SEQ ID NO: 160) R-H-L;(SEQ ID NO: 161) T-D-M-X-X-X-F-Q-A-D-F-T-S-L-S-N-Q-E-P-L-H-V

The HDX MS data for the cyno-PAI-1 peptides which showed significantprotection from exchange with APGv2 binding was analyzed to furtherdetermine the epitope for the cyno-PAI-1:APGv2 interact ion. The HDX MSepitope mapping data for A44v11 and APGv2 show that the epitopes are inthe same region, as seen generally in FIG. 52. In the region of residues307-321 the same peptides show protection in the antibody-bound statefor both A44v11 and APGv2. However, the magnitude of protection isgreater when cyno-PAI-1 is bound to A44v11 rather than APGv2 (see FIG.49(C)). This finding is more apparent in FIG. 52(B), which depicts thedifference peaks in the residue 307-321 region of cyno-PAI-1. Thisindicates that there are differences in the specific contacts madebetween cyno-PAI-1 and each of the A44V11 and APGv2 antibodies.Therefore, it appears that while the epitopes of both A44V11 and APGv2are located in a similar region of PAI-1, the epitopes for each antibodyare not the same.

1-15. (canceled) 16: An isolated monoclonal antibody that bindsspecifically to PAI-1, comprising: a heavy chain variable region that isat least 90% identical to the amino acid sequence of SEQ ID NO: 88 or 89and comprises a CDR1 region comprising the amino acid sequence of SEQ IDNO: 34, a CDR2 region comprising the amino acid sequence of SEQ ID NO:33, and a CDR3 region comprising the amino acid sequence of SEQ ID NO:32; and a light chain variable region that is at least 90% identical tothe amino acid sequence of SEQ ID NO: 91, 93, 94, 95, 96, or 97 andcomprises a CDR1 region comprising the amino acid sequence of SEQ ID NO:37, a CDR2 region comprising the amino acid sequence of SEQ ID NO: 36 orSEQ ID NO: 145, and a CDR3 region comprising the amino acid sequence ofSEQ ID NO:
 35. 17: An isolated monoclonal antibody that bindsspecifically to PAI-1, comprising: a heavy chain variable region that isat least 95% identical to the amino acid sequence of SEQ ID NO: 88 or 89and comprises a CDR1 region comprising the amino acid sequence of SEQ IDNO: 34, a CDR2 region comprising the amino acid sequence of SEQ ID NO:33, and a CDR3 region comprising the amino acid sequence of SEQ ID NO:32; and a light chain variable region that is at least 95% identical tothe amino acid sequence of SEQ ID NO: 91, 93, 94, 95, 96, or 97 andcomprises a CDR1 region comprising the amino acid sequence of SEQ ID NO:37, a CDR2 region comprising the amino acid sequence of SEQ ID NO: 36 orSEQ ID NO: 145, and a CDR3 region comprising the amino acid sequence ofSEQ ID NO:
 35. 18: An isolated monoclonal antibody that bindsspecifically to PAI-1, comprising: a heavy chain variable region that isat least 96% identical to the amino acid sequence of SEQ ID NO: 88 or 89and comprises a CDR1 region comprising the amino acid sequence of SEQ IDNO: 34, a CDR2 region comprising the amino acid sequence of SEQ ID NO:33, and a CDR3 region comprising the amino acid sequence of SEQ ID NO:32; and a light chain variable region that is at least 96% identical tothe amino acid sequence of SEQ ID NO: 96 or 97 and comprises a CDR1region comprising the amino acid sequence of SEQ ID NO: 37, a CDR2region comprising the amino acid sequence of SEQ ID NO: 36 or SEQ ID NO:145, and a CDR3 region comprising the amino acid sequence of SEQ ID NO:35. 19: The isolated monoclonal antibody of claim 18, wherein the heavychain variable region comprises the amino acid sequence of SEQ ID NO: 89and the light chain variable region is at least 96% identical to theamino acid sequence of SEQ ID NO: 97 and comprises a CDR1 regioncomprising the amino acid sequence of SEQ ID NO: 37, a CDR2 regioncomprising the amino acid sequence of SEQ ID NO: 36 or SEQ ID NO: 145,and a CDR3 region comprising the amino acid sequence of SEQ ID NO: 35.20: A method of restoring plasmin generation comprising administering toa subject in need thereof a pharmaceutically effective amount of theisolated monoclonal antibody of claim
 19. 21: The method of claim 20,wherein the pharmaceutically effective amount of the isolated monoclonalantibody is administered orally, parenterally by a solution forinjection, by inhalation, or topically. 22: The method of claim 20,wherein the method treats a condition comprising increased levels offibrotic tissue. 23: The method of claim 22, wherein the condition isfibrosis, systemic sclerosis, interstitial lung disease, chronic lungdisease, chronic kidney disease, peripheral limb ischemia, acuteischemic stroke with and without thrombolysis, or stent restenosis. 24:The method of claim 23, wherein the method treats a condition comprisingskin fibrosis, lung fibrosis, idiopathic pulmonary fibrosis, liverfibrosis, or kidney fibrosis. 25: The method of claim 23, wherein themethod treats a condition comprising venous and arterial thrombosis,deep vein thrombosis, or disseminated intravascular coagulationthrombosis. 26: A container comprising the isolated monoclonal antibodyof claim
 16. 27: The container of claim 26, wherein the container is aprefilled syringe, a vial, or an autoinjector. 28: A kit, comprising thecontainer of claim 26 and a label or instructions for administrationand/or use of the isolated monoclonal antibody. 29: A method forrestoring plasmin generation, treating increased levels of fibrotictissue, fibrosis, systemic sclerosis, interstitial lung disease, chroniclung disease, chronic kidney disease, peripheral limb ischemia, acuteischemic stroke with and without thrombolysis, or stent restenosis, skinfibrosis, lung fibrosis, idiopathic pulmonary fibrosis, liver fibrosis,kidney fibrosis, venous and arterial thrombosis, deep vein thrombosis,or disseminated intravascular coagulation thrombosis, comprisingadministering a pharmaceutically effective amount of the isolatedmonoclonal antibody of claim 16.